Sunan an-Nasa'i 4449

أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ أَبُو قُدَامَةَ السَّرَخْسِيُّ، قَالَ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ سُفْيَانَ، عَنْ مَنْصُورٍ، عَنْ عُمَارَةَ بْنِ عُمَيْرٍ، عَنْ عَمَّتِهِ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ إِنَّ أَطْيَبَ مَا أَكَلَ الرَّجُلُ مِنْ كَسْبِهِ وَإِنَّ وَلَدَ الرَّجُلِ مِنْ كَسْبِهِ ‏"‏ ‏.‏

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 a man's child (and his child's wealth) is part of his earnings" (Sahih)

Reference

Sunan an-Nasa'i 4449

In-book

Book 44, Hadith 1