Ikrimah, the freed slave of Ibn Abbas (may Allah be pleased with him), said: Ibn Abbas (may Allah be pleased with him) informed us that the mother of Sa'd bin Ubadah (may Allah be pleased with him) died while he was away from home. He came to the Messenger of Allah (peace and blessings be upon him) and said: "O Messenger of Allah! My mother has died and I was not with her at the time. If I give charity on her behalf, will it benefit her?" He (peace and blessings be upon him) said: "Yes." Sa'd (may Allah be pleased with him) said: "I make you my witness that my garden al-Mikhraf is charity on her behalf."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12631