"A woman traveled by sea and vowed to fast for a month, but she died before she could fast. Her sister came to the Prophet and told him about that, and he told her to fast on her behalf."  

أَنْ تَصُومَ فَأَتَتْ أُخْتُهَا النَّبِيَّ ﷺ وَذَكَرَتْ ذَلِكَ لَهُ فَأَمَرَهَا أَنْ تَصُومَ عَنْهَا