The mother of Sa`d bin 'Ubada died in his absence. He said, "O Allah's Messenger (ﷺ)! My mother died in
my absence; will it be of any benefit for her if I give Sadaqa on her behalf?" The Prophet (ﷺ) said, "Yes,"
Sa`d said, "I make you a witness that I gave my garden called Al Makhraf in charity on her behalf."
Sahih al-Bukhari Book 55, Hadith 19