Sunan Ibn Majah, Volume 3, Book 11, Hadith 2132 (DarusSalam) ⓘ

It was narrated from Ibn 'Abbas' that : Sa'd bin 'Ubadah asked the Messenger of Allah about a vow which his mother had made, but she had died without fulfilling it. The Messenger of Allah said: "Fulfill it on her behalf."

حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ سَعْدَ بْنَ عُبَادَةَ، اسْتَفْتَى رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ فِي نَذْرٍ كَانَ عَلَى أُمِّهِ تُوُفِّيَتْ وَلَمْ تَقْضِهِ فَقَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ اقْضِهِ عَنْهَا ‏" ‏ ‏.‏