Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him) said: I came to the Messenger of Allah (peace and blessings be upon him) and said: "My mother has died; she made no bequest and gave no charity. If I give charity on her behalf, will it be accepted?" He (peace and blessings be upon him) said: "Yes." He said: "Then will it benefit her?" He (peace and blessings be upon him) said: "Yes, even if it is only a burnt trotter of a goat."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5361