"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.'"
أَنَّهُ قَالَ مَاتَتْ أُمِّي وَعَلَيْهَا نَذْرٌ فَسَأَلْتُ النَّبِيَّ ﷺ فَأَمَرَنِي أَنْ أَقْضِيَهُ عَنْهَا
"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.'" (Using translation from Nasāʾī 3661)
أَنَّهُ قَالَ مَاتَتْ أُمِّي وَعَلَيْهَا نَذْرٌ فَسَأَلْتُ النَّبِيَّ ﷺ فَأَمَرَنِي أَنْ أَقْضِيَهُ عَنْهَا