The Prophet ﷺ said, "The best earnings are those of a worker who labors with his own hands and gives sincere effort."
عن النبي ﷺ قال: خير الكسب كسب يد العامل إذا نصح.
Imam Ahmad narrated it (8412, 8691) through two routes from Muhammad bin Ammar Kashakish, the muezzin of the masjid of the Messenger of Allah ﷺ, who said, "I heard Saeed Maqburi say, 'I heard Abu Hurairah,'" and he mentioned the hadith.Its isnad is hasan because of Muhammad bin Ammar bin Hafs bin Umar bin Saad Qaraz Madani, the muezzin, nicknamed Kashakish (with the first shin doubled), for his hadith is hasan.Ahmad said, "I see no harm in him."Ibn Madini said, "There was no harm in him."Ibn Madini also said, "He is trustworthy."Ibn Hibban mentioned him in Thiqat (7/436), and Haythami mentioned him in Majma (3/61) and said, "Its narrators are trustworthy."His saying, "when he is sincere," means when he is sincere in his work. This includes builders and scribes.