Sahih al-Bukhari 5320
Narrated Al-Miswer bin Makhrama:
Subai'a Al-Aslamiya gave birth to a child a few days after the death of her husband. She came to the 
Prophet and asked permission to remarry, and the Prophet (ﷺ) gave her permission, and she got married.
حَدَّثَنَا يَحْيَى بْنُ قَزَعَةَ، حَدَّثَنَا مَالِكٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنِ الْمِسْوَرِ بْنِ مَخْرَمَةَ، أَنَّ سُبَيْعَةَ الأَسْلَمِيَّةَ، نُفِسَتْ بَعْدَ وَفَاةِ زَوْجِهَا، بِلَيَالٍ فَجَاءَتِ النَّبِيَّ صلى الله عليه وسلم فَاسْتَأْذَنَتْهُ أَنْ تَنْكِحَ، فَأَذِنَ لَهَا، فَنَكَحَتْ‏.‏