Sahih al-Bukhari, Book 68, Hadith 67 (In-Book) ⓘ

Narrated Um Salama: (the wife of the Prophet) A lady from Bani Aslam, called Subai'a, become a widow while she was pregnant. Abu As-Sanabil bin Ba'kak demanded her hand in marriage, but she refused to marry him and said, "By Allah, I cannot marry him unless I have completed one of the two prescribed periods." About ten days later (after having delivered her child), she went to the Prophet and he said (to her), "You can marry now."

حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، عَنْ جَعْفَرِ بْنِ رَبِيعَةَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ هُرْمُزَ الأَعْرَجِ، قَالَ أَخْبَرَنِي أَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ، أَنَّ زَيْنَبَ ابْنَةَ أَبِي سَلَمَةَ، أَخْبَرَتْهُ عَنْ أُمِّهَا أُمِّ سَلَمَةَ، زَوْجِ النَّبِيِّ صلى الله عليه وسلم أَنَّ امْرَأَةً مِنْ أَسْلَمَ يُقَالُ لَهَا سُبَيْعَةُ كَانَتْ تَحْتَ زَوْجِهَا، تُوُفِّيَ عَنْهَا وَهْىَ حُبْلَى، فَخَطَبَهَا أَبُو السَّنَابِلِ بْنُ بَعْكَكٍ، فَأَبَتْ أَنْ تَنْكِحَهُ، فَقَالَ وَاللَّهِ مَا يَصْلُحُ أَنْ تَنْكِحِيهِ حَتَّى تَعْتَدِّي آخِرَ الأَجَلَيْنِ‏.‏ فَمَكُثَتْ قَرِيبًا مِنْ عَشْرِ لَيَالٍ ثُمَّ جَاءَتِ النَّبِيَّ صلى الله عليه وسلم فَقَالَ ‏ "‏ انْكِحِي ‏" ‏‏.‏