Musnad Ahmad 695:12

Hammad ibn Usamah narrated to us, Hisham informed us, from his father, from al-Miswar ibn Makhramah, that Subay'ah al-Aslamiyyah’s husband died while she was pregnant. She did not remain [in waiting] except for a few nights until she gave birth. When she recovered from her postpartum bleeding, she received marriage proposals. She sought permission from the Prophet, peace and blessings of Allah be upon him, to marry, and he permitted her to marry, so she married.