John Calvin Commentary Psalms 17:10

"They are inclosed in their own fat: With their mouth they speak proudly." — Psalms 17:10 (ASV)

They have inclosed themselves in their own fat. If the translation given by others, They have inclosed their own fat, is considered preferable, the meaning remains quite the same. Some Jewish interpreters explain these words in this way: that being stuffed with fat, and their throats, as it were, choked with it, they were unable to speak freely; but this is a very meager and unsatisfactory exposition.

By the word fat, I think, is denoted the pride with which they were filled and swollen, as it were, with fatness. It is a very appropriate and expressive metaphor to represent them as having their hearts choked up with pride, in the same way that corpulent persons are affected by the fat within them.

David complains of their being puffed up with their wealth and pleasures, and accordingly we see the ungodly, the more luxuriously they are pampered, conducting themselves the more outrageously and proudly. But I think there is described by the word fat an inward vice, namely, their being enclosed on all sides with arrogance and presumption, and their having become utter strangers to every feeling of humanity.

The Psalmist next declares that this is abundantly manifested in their language. In short, his meaning is, that inwardly they swell with pride, and that they make no effort to conceal it, as appears from the high-swelling words that they utter. When it is said, They have spoken proudly with their mouth, the word mouth is not a pleonasm, as it often is in other places; for David means that with mouths widely opened they pour forth scornful and contemptuous language, which testifies to the pride that dwells within them.