Verse 12. But above all things. That is, be especially careful on this point; whatever else is done, let not this be. The manner in which James speaks of the practice referred to here, shows that he regarded it as a sin of a very heinous nature; one that was by all means to be avoided by those whom he addressed. The habit of swearing by various things was a very common one among the Jews, and it was important to guard those who from among them had been converted to Christianity on that subject.

Swear not. See Barnes on "Mt 5:33-34"

for this command illustrated. Nearly the same things are mentioned here as objects by which they were accustomed to swear which are referred to by the Saviour.

But let your yea be yea. Let there be a simple affirmation, unaccompanied by any oath or appeal to God or to any of his works. A man who makes that his common method of speech is the man who will be believed. See Barnes on "Mt 5:37".

Lest ye fall into condemnation. That is, for profaning the name of God. "The Lord will not hold him guiltless that taketh his name in vain," Ex 20:7.

{a} "swear not" Mt 5:34