It was narrated from 'Amr bin Shu'aib from his father, that his a grandfather said:
"A man came to the Prophet (ﷺ) and said: 'I do not have anything and I have no wealth, but I have an orphan (under my care) who has wealth." He said: "Eat from the wealth of your orphan, without being extravagant or use it for trade." He (narrator) said: "And I think he said: 'Do not preserve your wealth using his instead.'"
English reference: Vol. 3, Book 22, Hadith 2718
Arabic reference: Book 22, Hadith 2822