A: The person in charge of bathing Imam Musa Kazim (a.s.) was apparently Sulaiman, cousin of His Eminence, but Imam Ridha’ (a.s.) arrived all the way from Medina to become the overseer of the funeral bath without anyone being able to recognize him. It is mentioned in Vol. 11 of Biharul Anwar that Ali bin Hamza asked the Imam:
"We have heard from your holy ancestors that none but only an Imam can perform the final rituals of a deceased Imam? (The questioner meant to say: You were in Medina when your father passed away in Baghdad). The Imam replied:
Was Imam Husain bin Ali an Imam or not? He replied: Yes, he was. The Imam asked: Who oversaw the burial of the Imam? That man replied: His son, Ali bin Husain (a.s.).
The Imam again asked: Where was Ali bin Husain at that time? In fact at that time, he was a prisoner of the cursed Ziyad.
Then he said: He came to Kerbala without anyone recognizing him, oversaw his father's burial and returned to the prison. The Imam said: The same God, Who gave such ability to Ali bin Husain (a.s.) also gave the power to the master of this affair (Imam of the time - Imam Ridha’) to come to Baghdad while he was not even in captivity.
As for the fact that Ahmad bin Musa was elder to Imam Ridha’ (a.s.); we have not found any such thing in books of traditions.
Sayyid Abdul Husayn Dastghaib