Then he says, that their mouth is full of cursing and bitterness [1] -- a vice of an opposite character to the former; but the meaning is, that they are in every way full of wickedness; for if they speak fair, they deceive and blend poison with their flatteries; but if they draw forth what they have in their hearts, bitterness and cursing stream out.

Footnotes

1 - Psalm 10:7. Paul corrects the order of the words as found in the Septuagint, and gives the Hebrew more exactly, but retains the word "bitterness," by which the Septuagint have rendered mrmvt, which means deceit, or rather, mischievous deceit. Some think that it ought to be mrrvt, "bitterness;" but there is no copy in its favor. -- Ed.

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

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