The Messenger of Allah ﷺ said, "The best of what a man eats is from his own earnings, and indeed a man's child is part of his earnings."
أخبرنا عبيد الله بن سعيد أبو قدامة السرخسي قال حدثنا يحيى بن سعيد عن سفيان عن منصور عن إبراهيم عن عمارة بن عمير عن عمته
قال رسول الله ﷺ إن أطيب ما أكل الرجل من كسبه وإن ولد الرجل من كسبه
[Its isnad is sahih] Abu Dawud narrated it in the Book of Business Transactions, chapter on the man who eats from his child's wealth, hadith no. 3528, from the hadith of Sufyan Thawri, with this wording, and it is also in al-Kubra, hadith no. 6043. Tirmidhi, hadith no. 1358, said it is hasan sahih, and Dhahabi graded it sahih.