Sahih al-Bukhari 2760
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 ‏"‏‏.‏