Whose mouth is full of cursing and bitterness. These words are taken from Ps 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", Mt 12:34.