Sahih al-Bukhari 5320
Sahih al-Bukhari · Book 68: Divorce · "For those who are pregnant, their 'Idda is until they laydown their burdens."
Narrated Al-Miswer bin Makhrama:
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.
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.