(2) باب وُصُولِ ثَوَابِ الصَّدَقَاتِ إِلَى الْمَيِّتِ
A'isha (Allah be pleased with her) reported that a man came to Allah's Apostle (ﷺ) and said:
Allah's Messenger, my mother died all of a sudden without making any will. I think if (she could have the opportunity) to speak she would have made a Sadaqa. Would there be any reward for her if I give charity on her behalf? He (the Holy Prophet) said: Yes.
Reference: Sahih Muslim 1004 d
In-book reference: Book 25, Hadith 18
USC-MSA web (English) reference(deprecated numbering scheme): Book 13, Hadith 4003