Sahih al-Bukhari, Volume 4, Book 51, Hadith 22 (USC-MSA) ⓘ
Narrated `Aisha: A man said to the Prophet, "My mother died suddenly, and I think that if she could speak, she would have given in charity. May I give in charity on her behalf?" He said, "Yes! Give in charity on her behalf."
حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي مَالِكٌ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، رضى الله عنها أَنَّ رَجُلاً، قَالَ لِلنَّبِيِّ صلى الله عليه وسلم إِنَّ أُمِّي افْتُلِتَتْ نَفْسَهَا، وَأُرَاهَا لَوْ تَكَلَّمَتْ تَصَدَّقَتْ، أَفَأَتَصَدَّقُ عَنْهَا قَالَ " نَعَمْ، تَصَدَّقْ عَنْهَا " .
also referenced under: Book 55, Hadith 23 (In-Book) & Hadith 2760 (DarusSalam)