That she was married to Sad bin Khaula who was from the tribe of Bani 'Amr bin Luai, and was one of those who fought the Badr battle. He died while she wa pregnant during Hajjat-ul-Wada.' Soon after his death, she gave birth to a child. When she completed the term of deliver (i.e. became clean), she prepared herself for suitors. Abu As-Sanabil bin Bu'kak, a man from the tribe of Bani Abd-ud-Dal called on her and said to her, "What! I see you dressed up for the people to ask you in marriage. Do you want to marry By Allah, you are not allowed to marry unless four months and ten days have elapsed (after your husband's death)." Subai'a in her narration said, "When he (i.e. Abu As-Sanabil) said this to me. I put on my dress in the evening and went to Messenger of Allah ﷺ and asked him about this problem. He gave the verdict that I was free to marry as I had already given birth to my child and ordered me to marry if I wished." (Using translation from Bukhārī 3991)
لَهَا رَسُولُ اللهِ ﷺ حِينَ اسْتَفْتَتْهُ فَكَتَبَ عُمَرُ بْنُ عَبْدِ اللهِ إِلَى عَبْدِ اللهِ بْنِ عُتْبَةَ يُخْبِرُهُ أَنَّ سُبَيْعَةَ أَخْبَرَتْهُ أَنَّهَا كَانَتْ تَحْتَ سَعْدِ بْنِ خَوْلَةَ وَهُوَ مِنْ بَنِي عَامِرِ بْنِ لُؤَيٍّ وَكَانَ مِمَّنْ شَهِدَ بَدْرًا فَتُوُفِّيَ عَنْهَا فِي حَجَّةِ الْوَدَاعِ وَهِيَ حَامِلٌ فَلَمْ تَنْشَبْ أَنْ وَضَعَتْ حَمْلَهَا بَعْدَ وَفَاتِهِ فَلَمَّا تَعَلَّتْ مِنْ نِفَاسِهَا تَجَمَّلَتْ لِلْخُطَّابِ فَدَخَلَ عَلَيْهَا أَبُو السَّنَابِلِ بْنُ بَعْكَكٍ رَجُلٌ مِنْ بَنِي عَبْدِ الدَّارِ فَقَالَ لَهَا مَالِي أَرَاكِ مُتَجَمِّلَةً لَعَلَّكِ تُرِيدِينَ النِّكَاحَ إِنَّكِ وَاللهِ مَا أَنْتِ بِنَاكِحٍ حَتَّى تَمُرَّ عَلَيْكِ أَرْبَعَةُ أَشْهُرٍ وَعَشْرٌ قَالَتْ سُبَيْعَةُ فَلَمَّا قَالَ لِي ذَلِكَ جَمَعْتُ عَلَيَّ ثِيَابِي حِينَ أَمْسَيْتُ فَأَتَيْتُ رَسُولَ اللهِ ﷺ فَسَأَلْتُهُ عَنْ ذَلِكَ فَأَفْتَانِي بِأَنِّي قَدْ حَلَلْتُ حِينَ وَضَعْتُ حَمْلِي «وَأَمَرَنِي بِالتَّزْوِيجِ إِنْ بَدَا لِي»