"She should observe 'Iddah for the longer of the two periods." Abu Salamah said: "No, it becomes permissible for her to marry when she has given birth." Abu Hurairah said: "I agree with my brother's son." So they sent word to Umm Salamah, the wife of the Prophet, and she said: "Subai'ah Al-Aslamiyyah gave birth shortly after her husband died; she consulted the Messenger of Allah and he told her to get married."
Sunan an-Nasa'i Book 27, Hadith 124
← Previous Hadith "It was said to Ibn 'Abbas concerning a woman who gives birth one day after her husband died: 'Can she get married?' He said: 'No, not until the longer of the two periods has ended.' He said: 'Allah says: And for those who are pregnant (whether they are divorced or their husbands are dead), their 'Iddah (prescribed period) is until they lay down their burden.' He said: 'That only applies in the case of divorce.' Abu Hurairah said: 'I agree with my brother's son' --meaning, Abu Salamah. He sent his slave Kuraib and told him: 'Go to Umm Salamah and ask her: Was this the Sunnah of the Messenger of Allah?' He came back and said: 'Yes, Subai'ah Al-Aslamiyyah gave birth twenty days after her husband died, and the Messenger of Allah told her to get married, and Abu As-Sanabil was one of those who proposed marriage to her.'"

Sunan an-Nasa'i Book 27, Hadith 123 Next Hadith → "Subai'ah gave birth a few days after her husband died, and the Messenger of Allah told her to get married."

Sunan an-Nasa'i Book 27, Hadith 125