Sayyiduna Abu Qatadah (may Allah be pleased with him) narrates that I heard the Messenger of Allah (peace and blessings be upon him) say: "The best things that a person leaves behind are three: a righteous child who prays for him, so his prayers reach him; or ongoing charity that he leaves behind, so its reward continues to reach him; or beneficial knowledge that he leaves behind, upon which people act (so he continues to receive its reward)."