It is narrated from Sayyidah Umm Sa'd bint Amr al-Jumahiyyah (may Allah be pleased with her); she said: I heard the Messenger of Allah (peace and blessings be upon him) saying: "Whoever takes care of an orphan, whether his own or someone else's, he and I will be together in Paradise like these two fingers."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21717