Narrated by:Narrated Ibn 'Abbas:
That Sa'd bin 'Ubadah asked the Messenger of Allah (ﷺ) about a vow that was due from his mother, who died before fulfilling it. The Prophet (ﷺ) said: "Fulfill it for her."
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا اللَّيْثُ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ سَعْدَ بْنَ عُبَادَةَ، اسْتَفْتَى رَسُولَ اللَّهِ صلى الله عليه وسلم فِي نَذْرٍ كَانَ عَلَى أُمِّهِ تُوُفِّيَتْ قَبْلَ أَنْ تَقْضِيَهُ فَقَالَ النَّبِيُّ صلى الله عليه وسلم اقْضِهِ عَنْهَا . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
Tirmizi
The Book on Vows and Oaths • Hadith 1581