Sahih al-Bukhari, Volume 4, Book 51, Hadith 19 (USC-MSA) ⓘ
Narrated Ibn `Abbas: The mother of Sa`d bin 'Ubada died in his absence. He said, "O Allah's Messenger! My mother died in my absence; will it be of any benefit for her if I give Sadaqa on her behalf?" The Prophet said, "Yes," Sa`d said, "I make you a witness that I gave my garden called Al Makhraf in charity on her behalf."
حَدَّثَنَا مُحَمَّدٌ، أَخْبَرَنَا مَخْلَدُ بْنُ يَزِيدَ، أَخْبَرَنَا ابْنُ جُرَيْجٍ، قَالَ أَخْبَرَنِي يَعْلَى، أَنَّهُ سَمِعَ عِكْرِمَةَ، يَقُولُ أَنْبَأَنَا ابْنُ عَبَّاسٍ ـ رضى الله عنهما ـ أَنَّ سَعْدَ بْنَ عُبَادَةَ ـ رضى الله عنه ـ تُوُفِّيَتْ أُمُّهُ وَهْوَ غَائِبٌ عَنْهَا، فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ أُمِّي تُوُفِّيَتْ وَأَنَا غَائِبٌ عَنْهَا، أَيَنْفَعُهَا شَىْءٌ إِنْ تَصَدَّقْتُ بِهِ عَنْهَا قَالَ " نَعَمْ " . قَالَ فَإِنِّي أُشْهِدُكَ أَنَّ حَائِطِي الْمِخْرَافَ صَدَقَةٌ عَلَيْهَا.
also referenced under: Book 55, Hadith 19 (In-Book) & Hadith 2756 (DarusSalam)