Sahih Bukhari Volume 4, Book 51, Hadith Number 24.

Narated By Ibn ‘Abbas : That the mother of Sad bin Ubada the brother of Bani Saida died in Sad’s absence, so he came to the Prophet saying, “O Allah’s Apostle! My mother died in my absence, will it benefit her if I give in charity on her behalf?” The Prophet said, “Yes.” Sad said, “I take you as my witness that I give my garden Al-Makhraf in charity on her behalf.”