Charles H. Spurgeon on Psalms 15:3

"He that backbiteth not with his tongue." The Hebrew word (Heb.) signifieth to play the spy, and by a metaphor, to backbite or slander, for backbiters and whisperers, after the manner of spies, go up and down dissembling their malice, that they may espy the faults and defects of others, whereof they may make a malicious relation to such as will give ear to their slanders. So that backbiting is a malicious defamation of a man behind his back. . . . . . And that the citizen of heaven doth and ought to abhor from backbiting, the horrible wickedness of this sin doth evince. For first, Leviticus 19:16, where it is straightly forbidden, the "tale-bearer" is compared to a pedlar: "Thou shalt not walk about with tales and slanders, as it were a pedlar among thy people." So much (Heb.) signifieth. For as the pedlar having bought his wares of some one or more goeth about from house to house that he may sell the same to others; so backbiters and tale-bearers, gathering together tales and rumours, as it were wares, go from one to another, that such wares as either themselves have invented, or have gathered by report, they may utter in the absence of their neighbour to his infamy and disgrace. Likewise Psalm 50:20, it is condemned as a notable crime, which God will not suffer to go unpunished; Ezekiel 22:9, it is reckoned among the abominations of Jerusalem, for which destruction is denounced against it; and Romans 1:29, 30, among the crimes of the heathen, given over unto a reprobate sense, this is placed: they were "whisperers and backbiters." George Downame.