Chapter 26: The Book of Wills
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.
Sahih Muslim 1004d