Excerpt from 'Nafasul Mahmum':
On the day of the battle of Malh, in the days on the ignorance, he was a Christian, he accepted Islam during the Caliphate of Umar bin Khattab. He had not yet recited the Namaz, when Umar made him the governor of a province, and he had not yet witnessed night when Imam Ali (a.s.) sent a proposal for the marriage of his daughter Rabab to Imam Husayn (a.s.). She was married to him and she bore him Abdullah (Ali Asghar) and Sakinah. Regarding Sakinah and her mother, Imam Husayn (a.s.) had said,
'By your life! I cherish the house in which there are Sakinah and Rabab, I endear them both and spend most of my wealth upon them, and there is no reason for censure in that, I shall not let them be neglected all throughout my life, until I am buried beneath the earth'.