Sunan an-Nasa'i, Hadith 4452 ⓘ
It was narrated that 'Aishah said: "The Messenger of Allah said: 'The best (most pure) food that a man eats is that which he has earned himself, and his child (and his child's wealth) is part of his earning."
أَخْبَرَنَا أَحْمَدُ بْنُ حَفْصِ بْنِ عَبْدِ اللَّهِ النَّيْسَابُورِيُّ، قَالَ حَدَّثَنِي أَبِي قَالَ، حَدَّثَنِي إِبْرَاهِيمُ بْنُ طَهْمَانَ، عَنْ عُمَرَ بْنِ سَعِيدٍ، عَنِ الأَعْمَشِ، عَنْ إِبْرَاهِيمَ، عَنِ الأَسْوَدِ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ أَطْيَبَ مَا أَكَلَ الرَّجُلُ مِنْ كَسْبِهِ وَإِنَّ وَلَدَهُ مِنْ كَسْبِهِ " .
also referenced under: Book 44, Hadith 4 (In-Book) & Volume 5, Book 44, Hadith 4457 (DarusSalam)