Ubaydullah bin Abdullah bin Utbah bin Mas'ud (may Allah have mercy on him) narrated from his father (Abdullah bin Utbah) that he wrote to Ibn al-Arqam: Ask Subay'ah al-Aslamiyyah (may Allah be pleased with her) what the Messenger of Allah (peace and blessings be upon him) instructed her when her husband died. She said: He gave me the ruling that once I had given birth, I could marry.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21118