Sahih Muslim Book 9, Hadith Number 3536.
Chapter: The period of ‘Idda comes to an end with the birth of the child.
‘Ubaidullah b. ‘Abdullah b. ‘Utba (b. Mas’ud) reported that his father wrote to Umar b. ‘Abdullah b al Arqam al-Zuhri that he would go to Subai’ah bint al-Hirith al-Aslamiyya (Allah be pleased with her) and ask her about a verdict from him which Allah’s Messenger (may peace be upon him) gave her when she had asked that from him (in regard to the termination of ‘Idda at the birth of a child) ‘Umar b. Abdullah wrote to ‘Abdullah b. ‘Utba informing him that Subai’ah had told him that she had been married to Sa’d b. Khaula and he belonged to the tribe of Amir b. Lu’ayy, and was one of those who participated in the Battle of Badr, and he died in the Farewell Pilgrimage and she had been in the family way at that time. And much time had not elapsed that she gave birth to a child after his death and when she was free from the effects of childbirth she embellished herself for those who had to give proposals of marriage. Abd al-Sunabil b. Ba’kak (from Banu ‘Abd al-Dar) came to her and said: What is this that I see you embellished ; perhaps you are inclined to marry, By Allah, you cannot marry unless four months and ten days (of ‘Idda are passed). When he said that. I dressed myself, and as it was evening I came to Allah’s Messenger (may peace be upon him) and asked him about it, and he gave me a religious verdict that I was allowed to marry when I had given birth to a child and asked me to marry if I so liked. Ibn Shihab said: I do not find any harm fur her in marrying when she has given birth to a child even when she is bleeding (after the birth of the child) except that her husband should not go near her until she is purified.