Muhammad bin 'Abdullah bin Yazid said:"Sufyan narrated to us from Az-Zuhri, from 'Ubaidullah bin 'Abdullah, from Ibn 'Abbas, that Sa'd said: 'My mother died and there was an (outstanding) vow that she had to fulfill. I asked the Prophet and he told me to fulfill it on her behalf.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ يَزِيدَ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ، عَنِ ابْنِ عَبَّاسٍ، عَنْ سَعْدٍ، أَنَّهُ قَالَ مَاتَتْ أُمِّي وَعَلَيْهَا نَذْرٌ فَسَأَلْتُ النَّبِيَّ صلى الله عليه وسلم فَأَمَرَنِي أَنْ أَقْضِيَهُ عَنْهَا.
Nesai
The Book of Wills • Hadith 3661