It is narrated from Sayyiduna Malik bin Amr (may Allah be pleased with him); he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever takes an orphan from between two Muslims into his food and drink until he no longer needs him, Paradise becomes definitely obligatory for him. And whoever frees a Muslim, that will be his ransom from the Fire: every limb of his (the freed person's) will save every limb of his."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16719