a woman came to the Messenger of Allah ﷺ and said: "My mother has died, and she had made a vow to fast, but she died before she could fulfill it. The Messenger of Allah ﷺ said: 'Let her guardian fast on her behalf ."
أَنَّ امْرَأَةً أَتَتْ رَسُولَ اللَّهِ ﷺ فَقَالَتْ إِنَّ أُمِّي تُوُفِّيَتْ وَعَلَيْهَا نَذْرُ صِيَامٍ فَتُوُفِّيَتْ قَبْلَ أَنْ تَقْضِيَهُ فَقَالَ رَسُولُ اللَّهِ ﷺ لِيَصُمْ عَنْهَا الْوَلِيُّ
Yahya related to me from Malik from Ibn Shihab from Ubaydullah ibn Abdullah ibn Utba ibn Masud from Abdullah ibn Abbas that Sad ibn Ubada questioned the Messenger of Allah ﷺ and said,"My mother died while she still had a vow which she had not fulfilled." The Messenger of Allah ﷺ said, "Fulfill it for her."
أَنَّ سَعْدَ بْنَ عُبَادَةَ اسْتَفْتَى رَسُولَ اللَّهِ ﷺ فَقَالَ إِنَّ أُمِّي مَاتَتْ وَعَلَيْهَا نَذْرٌ وَلَمْ تَقْضِهِ فَقَالَ رَسُولُ اللَّهِ ﷺ اقْضِهِ عَنْهَا