(19) بَابُ مَا يُسْتَحَبُّ لِمَنْ يُتَوَفَّى فَجْأَةً أَنْ يَتَصَدَّقُوا عَنْهُ، وَقَضَاءِ النُّذُورِ عَنِ الْمَيِّتِ
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."
Reference: Sahih al-Bukhari 2760
In-book reference: Book 55, Hadith 23
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 51, Hadith 22