If somebody dies without fulfiling a vow
حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي بِشْرٍ، قَالَ سَمِعْتُ سَعِيدَ بْنَ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ أَتَى رَجُلٌ النَّبِيَّ صلى الله عليه وسلم فَقَالَ لَهُ إِنَّ أُخْتِي نَذَرَتْ أَنْ تَحُجَّ وَإِنَّهَا مَاتَتْ. فَقَالَ النَّبِيُّ صلى الله عليه وسلم " لَوْ كَانَ عَلَيْهَا دَيْنٌ أَكُنْتَ قَاضِيَهُ ". قَالَ نَعَمْ. قَالَ " فَاقْضِ اللَّهَ، فَهْوَ أَحَقُّ بِالْقَضَاءِ ".
Narrated Ibn `Abbas: A man came to the Prophet (ﷺ) and said to him, "My sister vowed to perform the Hajj, but she died (before fulfilling it)." The Prophet (ﷺ) said, "Would you not have paid her debts if she had any?" The man said, "Yes." The Prophet (ﷺ) said, "So pay Allah's Rights, as He is more entitled to receive His rights."