John Gill Commentary Psalms 79:12

"And render unto our neighbors sevenfold into their bosom Their reproach, wherewith they have reproached thee, O Lord." — Psalms 79:12 (ASV)

And render to our neighbours seven fold into their bosom ,
ec.] Not seven fold for one, as the Targum paraphrases it, or a seven fold punishment for one sin; but that he would recompense their sins, or punish for them, and take vengeance on them, largely, abundantly, though not beyond measure, or exceeding the rules of justice; see (Genesis 4:15) (Luke 6:38) ,

the reproach with which they have reproached you, O Lord ;
by denying his being, or calling in question his perfections of power, truth, and goodness, to help his people; speaking ill of his providence, despising his word and ordinances, and even reproaching his people in reproaching him, (Psalms 89:50Psalms 89:51) , and this is what a righteous recompence is desired for; see .