Sahih Muslim Book 25, Hadith 17
My mother died all of a sudden, and I think if she (could have the opportunity) to speak she would have (made a will) regarding Sadaqa'. Will I be entitled to reward if I give charity on her behalf? He (the Holy Prophet) said: Yes.
My father died and left behind property without making any will regarding it. Would he be relieved of the burden of his sins if I give sadaqa on his behalf? He (the Holy Prophet) said: Yes.
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.