Hibatollah bin Abu Mansor al-Musily said that Yousuf bin Ya’qob the Christian had had relation with his father. Once, he came to his father as guest and his father asked him why he had come to Baghdad. He said, ‘It was sent for me to meet al-Mutawakkil and I did not know what for, but I bought myself with one hundred dinars that I gave to Ali bin Muhammad bin ar-Redha (Imam al-Hadi).’ Hibatollah added, ‘My father congratulated him, and then he left Baghdad towards Surra Man Ra’a. He stayed there for some days and then came back delightedly. My father asked him about his travel and he replied, ‘I arrived in Surra Man Ra’a, which I had not visited before. I liked to take the one hundred dinars to the son of ar-Redha (Imam al-Hadi) before I would go to meet al-Mutawakkil. I asked about him and it was said to me that al-Mutawakkil had prevented him from going out and that he kept to his house. I feared to visit him and refrained from asking about him. It came to my mind that I would ride on my sumpter and go to the town so that I might know something about him without asking. Walking in the streets and markets, I got to a house that it came to my mind it might be the house of Imam al-Hadi (a.s.). I asked my servant to see whose house it was. The servant asked and it was said to him that it was the house of the son of ar-Redha. My servant knocked the door and a black servant came out towards me and said, ‘Are you Yousuf bin Ya’qob?’ ‘Yes!’ I replied. He said, ‘Dismount!’ I dismounted from my sumpter and he took me into a vestibule. He went in and then came out asking me, ‘Where are the one hundred dinars?’ I gave them to him and he took them to the imam. After a while, he came and permitted me to come in. I came in. Imam al-Hadi (a.s.) was alone. He looked at me kindly and compassionately and said, ‘Is it not yet for you?-he meant (to be guided).’
I said, ‘O my master, a sufficient proof has appeared to me!’
Imam al-Hadi (a.s.) said, ‘How far! You will not be a Muslim, but your son will and he will be from our Shia. O Yousuf, there are some people claiming that our guardianship does not benefit ones like you. Go to what you have come to! You shall see what you like.’
Yousuf was astonished at the miracle he saw from Imam al-Hadi (a.s.). He went to al-Mutawakkil and got all that he wanted.
Hibatollah said, ‘Yousuf died and I met his son who was a good Muslim following the Ahlul Bayt (a.s.). He told me that his father was still Christian when he died, and that he (the son) became a Muslim after the death of his father. He often said, ‘I am the good tiding of my master’’ ( Bihar al-Anwar, vol.13 p.133.)