Bread of deceit is sweet to a man; Revised Version, bread of falsehood; i.e. bread gained without labour, or by unrighteous means (comp. Proverbs 10:2). This is agreeable because it is easily won, and has the relish of forbidden fruit. "Wickedness is sweet in his mouth" (Job 20:12). But afterwards his mouth shall be filled with gravel. He will find in his "bread" no nourishment, but rather discomfort and positive injury (comp. Job 20:14). The expression, "to eat gravel," is intimated in Lamentations 3:16, "He hath broken my teeth with gravel stones;" it implies grievous disappointment and unprofitableness. See here a warning against evil plesaures—
φεῦγ ἡδονὴν φέρουσαν ὕστερον βλάβην
"Sperne voluptates: nocet empta dolore voluptas."
Oort supposes that the gnome in the text is derived from a riddle, which asked, "What is sweet at first, but afterwards like sand in the mouth?"