It is narrated from Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him) that his mother died while he was away, so he asked the Prophet (peace and blessings be upon him): "Will it benefit her if I give charity on her behalf?" He (peace and blessings be upon him) said: "Yes."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5362