It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Sayyiduna Dawud (peace be upon him) used to eat only from the earnings of his own hands."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Imam al-Awza'i (may Allah have mercy on him) except al-Walid (may Allah have mercy on him), and Muhammad (may Allah have mercy on him) is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الألف / 1183
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 2073، 3417، 4713، وابن حبان فى «صحيحه» برقم: 6225، 6227، والبيهقي فى «السنن الكبرى» برقم: 11805، وأحمد فى «مسنده» برقم: 8276، والبزار فى «مسنده» برقم: 8734، والطبراني فى «الصغير» برقم: 17»