Sa`d bin Ubada consulted Allah's Messenger (ﷺ) saying, "My mother died and she had an unfulfilled vow." The Prophet (ﷺ) said, "Fulfill it on her behalf."
Sahih al-Bukhari Book 55, Hadith 24
← Previous Hadith A man said to the Prophet, "My mother died suddenly, and I think that if she could speak, she would have given in charity. May I give in charity on her behalf?" He said, "Yes! Give in charity on her behalf."

Sahih al-Bukhari Book 55, Hadith 23 Next Hadith → That the mother of Sa`d bin Ubada the brother of Bani Saida died in Sa`d's absence, so he came to the Prophet saying, "O Allah's Messenger (ﷺ)! My mother died in my absence, will it benefit her if I give in charity on her behalf?" The Prophet (ﷺ) said, "Yes." Sa`d said, "I take you as my witness that I give my garden Al-Makhraf in charity on her behalf."

Sahih al-Bukhari Book 55, Hadith 25