2 A man shall eat good by the fruit of his mouth: but the soul of the transgressors shall eat violence.
Note, 1. If that which comes from within, out of the heart, be good, and from a good treasure, it will return with advantage. Inward comfort and satisfaction will be daily bread; nay, it will be a continual feast to those who delight in that communication which is to the use of edifying.
2. Violence done will recoil in the face of him that does it: The soul of the transgressors that harbours and plots mischief, and vents it by word and deed, shall eat violence; they shall have their belly full of it. Reward her as she has rewarded thee, Rev. 18:6. Every man shall drink as he brews, eat as he speaks; for by our words we must be justified or condemned, Matt. 12:37. As our fruit is, so will our food be, Rom. 6:21, 22.
– Matthew Henry Commentary