If we are to embark on describing and narrating the lives of Imam Musa Kadhim and his children, we would need to write many books. This article gives a cursory look into the Imam's life and if you would like to learn more, you can refer to books authored by prominent Shi'ah scholars.
To be brief, we will now deal with the above question as follows:
Name, Titles and Lineage of Imam Musa Kadhim (AS)
His holy name was Musa son of Ja'far, son of Muhammad Baqir, son of Ali (Zainul Abedin), son of Hussein, son of Ali, son of Abu Talib.[1] Imam Musa Kadhim (A.S.) was born in Abwa [2] (a place between Makkah and Medina) on Sunday seventh of Safar 128 A.H. According to the most famous report[3], he was poisoned in the year 183 A.H.[4] in Harun al-Rashid's prison where he succumbed to death and was martyred.  He was then buried in the western part of Baghdad in a grave known as Quraish Cemetery.[5] That place is now known as Kadhemayn or al-Kadhemiyah.
Sheikh Mufid says: "In this graveyard Banu Hashim, tribal leaders and nobles used to be buried."[6]
Imam Kadhim's mother was called Hamidah Barbariyah.[7] She was also called Hamidah Musaffah[8] but Ibn Shahr Ashub is of the view that Hamidah Musaffah was the daughter of Sā'd Barbari nicknamed "Lu'lu'a", mother of Musa bin Ja'far (AS).[9]
'Abd Salih, Kadhim[10], Sabir[11] and Amin[12] are some of the nicknames of the Imam. Indeed, among these nicknames, Kadhim is the most famous of them.[13]
Sheikh Mufid says, Aba Ibrahim, Abal Hasan and Aba Ali are the Imam's patronymics.[14] Some have considered Abul Hasan, the First, Abu Ibrahim[15], and Abu Ismail [16] as his patronymics.
Imamate of Musa bin Ja'far (AS)
At the age of around 21, Imam Musa al-Kadhim (AS) undertook the exalted position of Imamate by the will of his father and the command of the Almighty Allah. His Imamate lasted a short while more than thirty five years, which was longer than other Imams except for the twelfth Imam, Imam Mahdi (AS). Fortunately, there are numerous reports substantiating and proving the imamate of the Imam (AS):
Ibn Sabbagh says, 'Abdul A'laa narrates from Faydh bin Mukhtar that he said to Imam Sadiq (AS): "Extend a helping hand to me and save me from the Fire by telling me who the Imam after you is." At the same time Musa bin Ja'far came up while he was still a child. Imam Sadiq (AS) pointed to him and said: "This is your Imam and you should turn to him."[17]
Skeikh Mufid says in this regard, "Musa bin Ja'far (AS) is the imam after his father. He precedes all other sons of Imam Sadiq (AS) because: 1- He was the most religious of the men of his time, the most knowledgeable in law, the most generous and the noblest in spirit. 2.  There are authentic and reliable traditions which explicitly refer to him. 3. His noble father clearly stated, "He is the successor and imam after me."[18]
Caliphs of the Time of Imam Musa bin Ja'far (AS)
The imamate (leadership) and wilayah (guardianship) of Imam Kadhim was simultaneous with the Abbasid caliphate. The Imam succeeded his noble father at a time when the most tyrant and oppressive rulers came to power.  It was a time when the Abbasid government was in full control of the affairs with no opposition and conflict taking place in Arabia. This stability and peace led the Abbasid government to easily control their opponents and monitor their actions and movements in the country.
A number of oppressive Abbasid rulers and sultans who lived in the time of Imam Kadhim are the following:
1. Mansur Dawaniqi: [19] He was the second Abbasd ruler after his brother Abu Abbas Saffah.[20] He was known to be jealous and envious and that was why he was nicknamed as 'Dawaniqi'.[21]
2. Mahdi Abbasi:[22] He was known for his excessive indulgence in debauchery, women, vile behavior, etc.[23] His passion for such things led his son Ibrahim to be the leader of singers and his daughter, Aliyah, to be among the singers and dancers of Baghdad.
3. Hadi Abbasi:[24] He took over the power when he was 25 years old[25]. He was very hostile to the family of the Holy Prophet (S). He was oppressive and cruel. His life was replete with pride and arrogance and characterized by a lack of experience. The period of his caliphate was among the difficult period of the Ahlulbayt (AS) and their followers.[26]
In his book titled "Muruj al-Zahab, Masudi, the famous historian writes: "He was cruel, ill-mannered and ill-natured."[27] The start of the revolutions and uprisings led by Banu Hashem and the Alawites was during the caliphate of Hadi Abbasi. The event of Fakh led by Hussein bin Ali was one of the most famous events of that period.[28] This movement was sanctioned by Imam Kadhim (AS) and the leader of the uprising (Hussein bin Ali) was promised martyrdom. The Imam (AS) advised to withstand difficulties and exercise patience. He said to him: "You will be killed, fight well, because the people who are standing against you are amongst the hypocrites."[29] This stance of the Imam puts the Fakh revolution to be amongst the healthiest of Aalwite revolutions against the Abbasids.[30]
4. Harun al-Rashid:[31]  He was known for collecting wealth, as well as for prodigality, having concubines, dancers and singers for entertainment.[32] He was extremely hostile to Banu Hashim and he made every effort to kill them.[33] To give an example, it was during his time that Musa bin Ja'far (AS) was imprisoned time and again and then was martyred in prison on the hands of Sindi bin Shahak.[34]
Imam Musa Kadhim's Stance against Harun al-Rashid
In spite of the fact that Harun al-Rashid was known for his arrogance, oppressiveness, cruelty, hardheartedness and hostility especially against the Alawites, we see in the history that Imam Kadhim (AS) was paying no heed to Harun and was never afraid of him. He stood firm and brave against him showing no sign of retreat and weakness against him. History stands witness to this fact. A few examples of the Imam's behavior towards Harun al-Rashid are cited as follows:
1. Harun al-Rashid and Pretention to be Related to Prophet (S)
Khatib Baghdadi has narrated from Abdur Rahman Ibn Salih ‘Azadi, “When Harun al-Rashid had gone to hajj, he went to the shrine of Messenger of Allah (S), along with a group of nobles from Quraysh and other Arab tribes. Musa Ibn Ja’far (AS) accompanied them too. When Harun reached the holy shrine, he said, ‘Greetings to you, o Messenger of Allah! O my cousin!’ He wanted to boast about his relationship with the Prophet (S). Then Musa Ibn Ja’far approached the grave and said, ‘Greetings to you, o my father!’ Hearing this, Harun’s face changed color and said, ‘O Abul Hassan! The real honor is about what you said.’”[35]
2. Showing Fadak Boundary to Harun al-Rashid
Fadak remained the symbol of the lost justice according to the Ahl al-Bayt (AS); for al-Zamakhshari says in his Rabi' al-Abrar, "Harun al-Rashid kept pressing Musa ibn Ja'fer (AS) to take Fadak back, and he kept refusing.
When he insisted that he should, he said, `I shall not take it back except in its boundaries.' He asked him, `And what are its boundaries?' He said, `The first is Aden;' al-Rashid's face changed color and he asked him, `And what is the second boundary?' He said Samarkand;' now his face started shaking in outrage.
He asked him, `And what is the third boundary?' He said, `Africa;' and the caliph's face now turned black in anger, yet he asked him, `And what is the fourth boundary?' He said, `The ocean, and whatever is beyond the Caspian Sea and Armenia.'
Harun al-Rashid then said, `There is nothing left for us; so, come and take my throne as well!' The Imam (AS) said, `I had told you before that if I defined its boundaries, you would refuse to give it back to me.' It was then that Harun decided to kill him."[36]
3. Proving relation to the Messenger of Allah (S)
Once Harun Al-Rashid said to Imam Kadhim (AS), “How can you claim to be from the children of the Prophet when in reality you are from the children of Ali, and every person’s lineage returns back to their paternal grandparents, not their maternal”. Imam Kadhim (as) replied using a verse from the Holy Qur’an ‘...and from his (Ibrahims) offspring, David and Solomon, Job, Joseph, Moses and Aaron, Thus do We reward the virtuous. And Zechariah, John, Jesus and Ilyas, each of them among the righteous."[37]
He went on to explain the verse sighting that in it Jesus had been counted amongst the children of the previous Prophets, even though he was related to them through his mother, not his father. In the same way, he explained, we (the Ahl al-Bayt) are related to and counted as the children of the Prophet (saw) through our mother Fatima (SA). As well, God the Exalted says in the Holy Quran: "But whoever disputes with you in this matter after what has come to you of knowledge, then say: Come let us call our sons and your sons and our women and your women and our near people and your near people, then let us be earnest in prayer, and pray for the curse of Allah on the liars."[38]
During the malediction (mubahalah), the Prophet (S) peace did not invite anyone to go out with him except Ali, Fatima, Hasan and Hussein (AS). So, Hasan and Hussein are the Prophet's children.[39]
Imam Kadhim's Knowledge and Moral Virtues
Imam Musa peace be upon him was the most religious of the men of his time, the most knowledgeable in law, the most generous and the noblest in spirit. There are numerous accounts and narrations about his moral and spiritual virtues keeping in view the fact that he was brought up in the house of prophethood where angels descended.
Here we shall cite three narrations in regard to the Imam's virtues:
A) Abu Hanifa says, after I had performed the hajj I went to Medina to visit Aba Abdillah As-Sadiq (A.S.). I entered his house and sat in the entrance waiting for his permission. After a while, a male toddler went out.
"O boy," I asked, "where should the stranger excrete in your country?" The boy asked for a respite before he sat to a wall and spoke: You should be away from riversides, places were fruits fall, yards of mosques, and roadbeds.
You should also hide against a wall, lift up your dress, avoid turning the face or the back to the Qiblah and then you can excrete any where. I was highly admired by the wording of that boy. I therefore asked about his name.
"I am, Musa bin Ja'far", answered he. I then asked him about the source of the acts of disobedience to Allah, He answered: The source of any sin is unquestionably one of three: either the Allah, the Allah and the servant, or the servant. If Allah is the source of sins, yet He is not, then it is improper for Him to punish the servants for what they did not commit.
If Allah and the servants are together the source of sin, yet this is not accurate, then it is improper for the stronger partner to wrong the weak partner. If the servant is the source of the sins - and this is quite accurate-, then the Lord may pardon out of His generosity and liberty to punish for the commitment of such a sin. After I had heard so, I left before I could meet Abu Abdillah (Imam Sadiq) since that wording was sufficient for me.
Abu Hanifa says, 'Then I said: " They were descendants of one of another. [40] "[41]
Scholars have narrated different traditions on various sciences and branches of science. Our religious texts are replete with these sciences.[42]
B) Abul Faraj Isfahani says that Yahya bin Hasan narrated to him that: A man from the family of the Second Caliph was in Medina trying to harm Imam Musa, peace be on him. Whenever he saw (Abu al-Hasan) he would curse him and curse Ali, peace be on him. One day some of those who used to attend his gatherings said to him: "Let us kill this sinner."
He forbade them from (doing) that most firmly and rebuked them severely.
He asked about the descendant of  the Second Caliph and was told that he had a farm on the outskirts of Medina. He rode out to him and found him at his farm. As he entered the farm with his donkey, the descendant of the caliph cried out: "Do not tread on my sown land."
Yet Imam Musa, peace be on him, continued to tread on it with his donkey until he reached him. He dismounted and sat with him. He greeted him with a smile and laughed at him.
"How much have you paid to sow your land?" he asked.
"One hundred dinars," (the other man) answered. "How much do you hope to acquire from it?" Imam al-Kadhim asked.
"I do not know the unknown," was the reply.
"I only asked you about what you hope it would bring you," said the Imam.
"I hope that it will bring me two hundreds dinars," he answered. Imam Musa Kadhim took out a purse in which was three hundred dinars and said: "This is (the price) of what you have sown in its present condition (i.e. what you have spent to sow it and what you hope to gain from it). May Allah provide you with what you hope for from it."
The descendant of the Second Caliph rose up and kissed his hand and asked him to forgive him his (former) hasty words about him. Imam Kadhim, peace be on him, smiled at him and went away.
In the evening Imam Hasan went to the mosque and found that descendant of 'Umar sitting there. When the latter saw him, he called out: "Allah knows best where to put His (prophetic) mission." His companions jumped (in surprise) towards him and said to him: "What is the story (behind what you say), for you used to speak quite differently from this."
"You have heard what I have said now," he replied and began to speak on behalf of Imam Kadhim, peace be on him. They opposed him and he opposed them.
When Imam Kadhim returned to his house, he said to those who attained his gatherings and who had asked about killing the descendant of the Second Caliph: "Which was better-what you wanted or what I did?[43]"
C) Imam Kadhim (AS) used to pray supererogatory prayers throughout the night so that he would make them extend until the morning prayer, then continue them until the sun rose. He would remaining prostrating himself before Allah without raising his head from prayer and praising Allah until the sun came near to descending (from its midday zenith)."
Another example of his acts of worship is that at the beginning of the night, he entered the mosque of his grandfather, Allah's Messenger, may Allah bless him and his Household, prostrated himself before Allah, and said with fear of Him: "How great sin is with me! Therefore let forgiveness seem good to You, O Worthy of reverential fear, O Worthy to forgive!"
The Imam (AS) used to recite this dua:
«اللَّهُمَّ إِنِّي أَسْأَلُكَ الرَّاحَةَ عِنْدَ الْمَوْتِ وَ الْعَفْوَ عِنْدَ الْحِسَابِ»
'O Allah, I ask you ease at death and to forgive me (on the day) of Reckoning.'
He continued this supplication with turning to Allah in repentance, sincerity, and weeping to the extent that his beard would be wet with tears.[44] He was the kindest of men to his family and his kin. He used to search out the poor of Medina during the night and take them a basket, in which was money, flour and dates. He would take that to them without them knowing in any way that it was from him.[45]
Number of His Sons and Their Names
As we mentioned in the beginning of this article, we would need to write many books, if we have to provide a detailed report on the life of Imam Musa Kadhim (AS) and his children. However, we would suffice to mentioning the names of his sons and daughters and the reader can refer to other sources for further information:
Abu al-Hasan Musa, peace be on him, had thirty seven children male and female. They were:  Hazrat Reza (AS), Ibrahim, Abbas and Qasim each having separate mothers.
Ahmad, Muhammad and Hamzah whose mothers were slave-wives. Isamail, Ja'far, Harun and Hasan whose mother was also a slave-wife. Abdullah, Ishaq, Ubaidullah, Zaid, Hasan, Fazl and Sulayman whose mothers were also slave-wives.  Fatima Kubra, Fatima Sughra, Hakimah, Umm Abihā, Ruqayyah Sughra, Kulthum, Umm Ja'far, Labanah, Zainab, Khadijah, Aliyah, Amenah, Hasanah, Buraihah, Aishah, Umm Salamah, Maymoonah, Umm Kulthum. These daughters were also from different mothers.[46]
Some historians have added some other names to these which we are not going to mention for the sake of brevity.

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