They are enclosed in their own fat: with their mouth they speak proudly.
To be enclosed in one's own fat means, to be wrapped up in pride and self-complacency, the effect upon weak and ignoble minds of worldly prosperity. It is said that the purely fatty part of the human body, having no nerves of sensation, can be cut and pierced without experiencing any feeling of pain. Hence, in Scripture phraseology, to say that one's heart is fat is equivalent to saying that it is hard and insensible, void of moral and sympathetic feeling, and not to be affected by any appeal made to its pity or sense of right. It indicates a haughtiness and insolence of bearing towards others that is hard to be borne by them. Alas! how a little worldly elevation sometimes changes the best character into the worst! How it renders the man proud who before was humble; the heart hard that before was tender! To be delivered from the tender mercies of mindless wealth, of heartless prosperity, is a prayer that others besides David have breathed into the ear of Divine mercy. It was not the poor, but the proud, the prosperous, the high in station and authority, that chased the Son of God to the Cross, and reviled Him there.
(David Caldwell, A. M.)
Parallel VersesKJV: They are inclosed in their own fat: with their mouth they speak proudly.