Sahih Bukhari
Prophets
Volume: 004 / Book Number: 055 / Hadith Number: 628
Narrated Abu Huraira:
The Prophet said, "The reciting of the Zabur (i.e. Psalms) was made easy for David. He used to order that his riding animals be saddled, and would finish reciting the Zabur before they were saddled. And he would never eat except from the earnings of his manual work."