[Machine] A woman came to the Prophet ﷺ and informed him that her sister had made a vow to fast for a month, but she died before being able to fulfill it because she had embarked on a sea voyage. The Prophet ﷺ then told her, "I will fast on behalf of your sister." This statement indicates that the Prophet ﷺ granted permission to fast on behalf of another person, just as she had intended.
أَنَّ امْرَأَةً أَتَتِ النَّبِيَّ ﷺ فَذَكَرَتْ لَهُ أَنَّ أُخْتَهَا نَذَرَتْ أَنْ تَصُومَ شَهْرًا وَأَنَّهَا رَكِبَتِ الْبَحْرَ فَمَاتَتْ وَلَمْ تَصُمْ فَقَالَ لَهَا رَسُولُ اللهِ ﷺ صُوْمِي عَنْ أُخْتِكِ فَهَذَا اللَّفْظُ نَصٌّ فِي الصَّوْمِ عَنْهَا وَكَذَلِكَ