His mouth is full of cursing and deceit and fraud: under his tongue is mischief and vanity.
Read Chapter 10
Augustine of Hippo
5. "Whose mouth is full of cursing and bitterness and deceit" (ver. 7). For it is a great curse to seek heaven by such abominable arts, and to get together such earnings for acquiring the eternal seat. But of this cursing his mouth is full. For this desire shall not take effect, but within his mouth only will avail to destroy him, who dared promise himself such things with bitterness and deceit, that is, with anger and insidiousness, whereby he is to bring over the multitude to his side. "Under his tongue is toil and grief." Nothing is more toilsome than unrighteousness and ungodliness: upon which toil follows grief; for that the toil is not only without fruit, but even unto destruction. Which toil and grief refer to that which he hath said in his heart, "I shall not be moved from generation to generation without evil." And therefore, "under his tongue," not on his tongue, because he will devise these things in silence, and to men will speak other things, that he may appear good and just, and a son of God.