It is narrated from Nafi' (may Allah have mercy on him) from Ibn Umar (may Allah be pleased with him) that he used to give zakat from the wealth of the orphan.
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 716
Hadith Takhrijاسناده صحيح اخرجه البيهقى 4 / 108 ، 149 ۔ وعبد الرزاق (6991) ۔ (6998) وابن ابي شيبة (10116)۔