Whose mouth - Psalm 10:7. The apostle has not quoted this literally, but has given the sense. David in the psalm is describing his bitter enemies.

Cursing - Reproachful and opprobrious language, such as Shimei used in relation to David; 2 Samuel 16:5, 2 Samuel 16:7-8.

Bitterness - In the psalm, deceits. The word "bitterness" is used to denote severity, harshness, cruelty; reproachful and malicious words.

Whose mouth is full of cursing, etc. - They never speak but in profane oaths, blasphemies, and malice.

Whose mouth is full of cursing and bitterness. These words are taken from Psalm 10:7, by cursing is meant, cursing of God, which is sometimes internal with the heart, and sometimes external with the mouth, as here; and of all good men, though without cause, and to no purpose with respect to the persons they curse, since God has blessed them, and they are blessed, and greatly to their own detriment, for, in the issue, their curses will be turned against themselves. There is also a cursing of superiors, as parents, masters, magistrates, kings, and governors; which is a sore evil, and attended with bad consequences; likewise of themselves, and their fellow creatures: and "the mouth being full of it", denotes the frequency of the sin; scarce anything else comes out of it but cursing; which discovers the sad corruption of the heart; "for out of the abundance of the heart the mouth speaketh", Matthew 12:34. By "bitterness" is meant, either sin in general, which is "an evil and bitter thing", Jeremiah 2:19, in its nature and effects; or sinful words, such as oaths, curses, imprecations, all wrathful and deceitful words.

Whose mouth is full of cursing and bitterness:

3:14 Cursing - Against God. Bitterness - Against their neighbour. Psalm 10:7.

14. Whose mouth, &c.-(Ps 10:7): that is, "That mouth which should be 'most sweet' (So 5:16), being 'set on fire of hell' (Jas 3:6), is filled with burning wrath against those whom it should only bless."

3:9-18 Here again is shown that all mankind are under the guilt of sin, as a burden; and under the government and dominion of sin, as enslaved to it, to work wickedness. This is made plain by several passages of Scripture from the Old Testament, which describe the corrupt and depraved state of all men, till grace restrain or change them. Great as our advantages are, these texts describe multitudes who call themselves Christians. Their principles and conduct prove that there is no fear of God before their eyes. And where no fear of God is, no good is to be looked for.