In the period of the second caliph “Ummer”, the Muslims conquered Iran. The daughters of Yazdgard were brought to Madina.
All had gathered in the mosque of Madina to see what was the decision of the caliph, about them. He wanted to sell them but Imam Ali (A.S.) stopped him from doing so and said to Urnmer, “leave the girls free so that they marry whosoever they wish.”
One of the girls chose Hussain Ibn-e-Ali (A.S.) and the other chose Imam Hassan Mujtaba (A.S.). Imam Ali (A.S.) said to Hussain, “Look after this woman very well, because, from her an Imam will come into existence (born) who will be the best of the God’s creations upon the earth and the father of all the Imams (after himself).