Hadith 13:18
Narrated Ibn Abbas (RA):
Sa'd bin Ubada asked Allah's Messenger (ﷺ) for a ruling regarding a vow taken by his mother who had died before fulfilling it, and he said, "Fulfill it on her behalf." [Agreed upon].
وَعَنْ اِبْنِ عَبَّاسٍ رَضِيَ اَللَّهُ عَنْهُمَا قَالَ: { اِسْتَفْتَى سَعْدُ بْنُ عُبَادَةَ - رضى الله عنه - رَسُولَ اَللَّهِ - صلى الله عليه وسلم -فِي نَذْرٍ كَانَ عَلَى أُمِّهِ, تُوُفِّيَتْ قَبْلِ أَنْ تَقْضِيَهُ ? فَقَالَ: "اِقْضِهِ عَنْهَا" } مُتَّفَقٌ عَلَيْهِ
Original Reference: Bulugh al-Maram 1391