Hadith 12:27
Ibn ‘Abbas told that Sa'd b. ‘Ubada asked the Prophet for a decision about a vow taken by his mother who had died before fulfilling it, and that he gave decision that he should fulfil it on her behalf. (Bukhari and Muslim.)
وَعَنِ ابْنِ عَبَّاسٍ: أَنَّ سَعْدَ بن عبَادَة رَضِي الله عَنْهُم اسْتَفْتَى النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي نَذْرٍ كَانَ عَلَى أُمِّهِ فَتُوُفِّيَتْ قَبْلَ أَنْ تَقْضِيَهُ فَأَفْتَاهُ أَنْ يَقْضِيَهُ عَنْهَا
Original Reference: Mishkat al-Masabih 3433