When a pregnant widow gives birth, it is permissible for her to remarry

It was narrated that Abu Sanabil said:
"Subai'ah Aslamiyyah bint Harith gave birth twenty-odd days after her husband died. When her postnatal bleeding ended, she adorned herself, and was criticized for doing that. Her case was mentioned to the Prophet ﷺ and he said: 'If she does that, then her waiting period is over."'

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ مَنْصُورٍ، عَنْ إِبْرَاهِيمَ، عَنِ الأَسْوَدِ، عَنْ أَبِي السَّنَابِلِ، قَالَ وَضَعَتْ سُبَيْعَةُ الأَسْلَمِيَّةُ بِنْتُ الْحَارِثِ حَمْلَهَا بَعْدَ وَفَاةِ زَوْجِهَا بِبِضْعٍ وَعِشْرِينَ لَيْلَةً فَلَمَّا تَعَلَّتْ مِنْ نِفَاسِهَا تَشَوَّفَتْ فَعِيبَ ذَلِكَ عَلَيْهَا وَذُكِرَ أَمْرُهَا لِلنَّبِيِّ ﷺ فَقَالَ " إِنْ تَفْعَلْ فَقَدْ مَضَى أَجَلُهَا " .

It was narrated that Masruq and 'Amr bin 'Utbah wrote to Subai'ah bint Harith, asking about her case.:
She wrote to them saying that she gave birth twenty-five days after her husband died. Then she prepared herself, seeking to remarry. Abu Sanabil bin Ba'kak passed by her and said: "You are in a hurry; observe waiting period for the longer period, four months and ten days." "So I went to the Prophet ﷺ and said: 'O Messenger of Allah, ﷺ pray for forgiveness for me.' He said: 'Why is that.” I told him (what had happened). He said: 'If you find a righteous husband then marry him."'

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ دَاوُدَ بْنِ أَبِي هِنْدٍ، عَنِ الشَّعْبِيِّ، عَنْ مَسْرُوقٍ، وَعَمْرِو بْنِ عُتْبَةَ، أَنَّهُمَا كَتَبَا إِلَى سُبَيْعَةَ بِنْتِ الْحَارِثِ يَسْأَلاَنِهَا عَنْ أَمْرِهَا، فَكَتَبَتْ إِلَيْهِمَا إِنَّهَا وَضَعَتْ بَعْدَ وَفَاةِ زَوْجِهَا بِخَمْسَةٍ وَعِشْرِينَ فَتَهَيَّأَتْ تَطْلُبُ الْخَيْرَ فَمَرَّ بِهَا أَبُو السَّنَابِلِ بْنُ بَعْكَكٍ فَقَالَ قَدْ أَسْرَعْتِ اعْتَدِّي آخِرَ الأَجَلَيْنِ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا . فَأَتَيْتُ النَّبِيَّ ﷺ فَقُلْتُ يَا رَسُولَ اللَّهِ اسْتَغْفِرْ لِي . قَالَ " وَمِمَّ ذَاكَ " . فَأَخْبَرْتُهُ . فَقَالَ " إِنْ وَجَدْتِ زَوْجًا صَالِحًا فَتَزَوَّجِي " .

It was narrated from Miswar bin Makhramah that:
the Prophet ﷺ told Subai'ah to get married, when her postnatal bleeding ended.

حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ، وَمُحَمَّدُ بْنُ بَشَّارٍ، قَالاَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دَاوُدَ، حَدَّثَنَا هِشَامُ بْنُ عُرْوَةَ، عَنْ أَبِيهِ، عَنِ الْمِسْوَرِ بْنِ مَخْرَمَةَ، أَنَّ النَّبِيَّ ﷺ أَمَرَ سُبَيْعَةَ أَنْ تَنْكِحَ إِذَا تَعَلَّتْ مِنْ نِفَاسِهَا .