Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) reports this saying of the Prophet (peace and blessings be upon him): "Whoever takes care of an orphan of his own (family) or of another (family), Paradise becomes binding for him; however, the ruling is different if he has committed a deed that cannot be forgiven."
Imam Tabarani recorded it; its chain contains a narrator, Dawud bin al-Zibriqan, and he is matruk (abandoned).