Sayyiduna Abu al-Sanabil bin Ba'kak (may Allah be pleased with him) said: Sayyidah Subay'ah bint al-Harith (may Allah be pleased with her) gave birth some twenty-odd nights after the death of her husband. When she became pure from her postnatal bleeding, she showed a desire (for marriage), and she was reproached for it. Then her case was presented to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "If she does so, her waiting period ('iddah) has been completed."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 19099