Sunan an-Nasa'i, hadith 3816

أَخْبَرَنَا بِشْرُ بْنُ خَالِدٍ الْعَسْكَرِيُّ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، عَنْ شُعْبَةَ، قَالَ سَمِعْتُ سُلَيْمَانَ، يُحَدِّثُ عَنْ مُسْلِمٍ الْبَطِينِ، عَنِ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ رَكِبَتِ امْرَأَةٌ الْبَحْرَ فَنَذَرَتْ أَنْ تَصُومَ شَهْرًا فَمَاتَتْ قَبْلَ أَنْ تَصُومَ فَأَتَتْ أُخْتُهَا النَّبِيَّ صلى الله عليه وسلم وَذَكَرَتْ ذَلِكَ لَهُ فَأَمَرَهَا أَنْ تَصُومَ عَنْهَا ‏.‏

It was narrated that Ibn 'Abbas said:"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