One day Imam Husayn (a.s) was somewhat displeased with Muhammad Hanafiyah. Some of his friends told him that now Imam Husayn (a.s) would never come to him. To this he replied that Imam Husayn (a.s) was very kind-hearted and he would definitely forgive his mistake. Then he wrote a letter as follows:
Respected Brother,
The father of both of us is Ali (a.s). Thus from the aspect of paternity neither you have any precedence nor me. However, you mother is the daughter of the Messenger of Allah (S). If all the gold and the silver of the world come into the ownership of my mother, she cannot be compared to your mother. Thus you have a great superiority over me. I desire that you bless me with your visit and increase my honor.”
As soon as he read the letter, the Imam arose and came to Muhammad Hanafiyah.
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams