Adam Clarke on Psalms 119:119

Thou puttest away all the wicked of the earth like dross - There is no true metal in them: when they are tried by the refining fire, they are burnt up; they fly off in fumes, and come to no amount. There is probably an allusion here to the scum or scorias at the surface of melting metals, which is swept oft previously to casting the metal into the mould.

Therefore I love thy testimonies - Thy testimonies will stand; and thy people will stand; because thou who didst give the one, and who upholdest the other, art pure, immovable, and eternal.