وَعَنِ ابْنِ عَبَّاسٍ
أَنَّ سَعْدَ بن عبَادَة رَضِي الله عَنْهُم اسْتَفْتَى النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي نَذْرٍ كَانَ عَلَى أُمِّهِ فَتُوُفِّيَتْ قَبْلَ أَنْ تَقْضِيَهُ فَأَفْتَاهُ أَنْ يَقْضِيَهُ عَنْهَا
Ibn Abbas told that Sad ibn Ubada asked the Prophet (sallallahu alayhi wa sallam) for a decision about a vow taken by his mother who had died before fulfilling it, and that he gave decision that he should fulfil it on her behalf.
Mishkat al-Masabih 3299, Book 16, Oaths and Vows, Hadith 27. 1 min read