It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her); she said: Subay'ah bint al-Harith gave birth a few days after the death of her husband, and the Messenger of Allah (peace and blessings be upon him) ordered her to marry.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19878