Sahih Muslim | Book 13 | Hadith Number 4002

Narrated by 'Aisha (Allah be pleased with her)
'Aisha (Allah be pleased with her) reported that a man said to Allah's Apostle (may peace be upon him): 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.