It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs Hajj on behalf of his father or his mother, it suffices for him and for both of them."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5064