It is narrated from Sayyiduna al-Miswar bin Makhramah (may Allah be pleased with him) that the husband of Subay'ah al-Aslamiyyah (may Allah be pleased with her) died while she was pregnant, and not even a few nights had passed before she gave birth. When she had recovered from her postnatal bleeding (nifas), she asked the Prophet (peace and blessings be upon him) for permission, and he (peace and blessings be upon him) gave her permission, and she married.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17147