Isaiah 1:16

Wash ye, make you clean, c. These two words are to be regarded as one, since they intend the same thing, and suppose the persons spoken to to be unclean, as they were, notwithstanding their legal sacrifices and ceremonial ablutions and are designed to convince them of it, to bring them to a sense of their inability to cleanse themselves, to lead them to inquire after the proper means of it, and so to the fountain of Christ's blood to wash in, which only cleanses from it:

put away the evil of your doings from before mine eyes; the exhortation is not barely to put away their doings, but the evil of them, and that not from themselves, but from before the eyes of God, from the eyes of his vindictive justice, which is only done by the sacrifice of Christ; and the use of this exhortation is to show the necessity of putting away sin to salvation, and the insufficiency of the blood of bulls and goats to do it, since, notwithstanding these, it remains untaken away; and to direct to the sacrifice of Christ, which effectually does it.

Cease to do evil; either from ceremonial works done with a wicked mind, or from outward immoralities, such as shedding innocent blood, oppressing the fatherless and widow, things mentioned in the context; it denotes a cessation from a series and course of sinning, otherwise there is no ceasing from sin in this life.