From Sahih Bukhari (Hadith 2770):
Narrated Ibn `Abbas:A man said to Allah's Messenger (ﷺ) , "My mother died, will it benefit her if I give in charity on her behalf?" The Prophet (ﷺ) replied in the affirmative. The man said, "I have a garden and I make you a witness that I give it in charity on her behalf
Reference: Bukhari 2770