Sunan an-Nasa'i, Hadith 3654 ⓘ
It was narrated from Ibn 'Abbas that Sa'd asked the Prophet: "My mother died and did not leave a will; shall I give charity on her behalf?" He said: "Yes."
أَخْبَرَنَا الْحُسَيْنُ بْنُ عِيسَى، قَالَ أَنْبَأَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ سَعْدًا، سَأَلَ النَّبِيَّ صلى الله عليه وسلم إِنَّ أُمِّي مَاتَتْ وَلَمْ تُوصِ أَفَأَتَصَدَّقُ عَنْهَا قَالَ " نَعَمْ " .
also referenced under: Book 30, Hadith 44 (In-Book) & Volume 4, Book 30, Hadith 3684 (DarusSalam)