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…”

“God saith to the sinner, "Wash you," &c., that he, finding his inability to "make" himself "clean," may cry to God, Wash me, cleanse me (Psa 51:2, Psa 51:7, Psa 51:10). before mine eyes--not mere outward reformation before man's eyes, who cannot, as God, see into the heart (Jer 32:19).”

“Wash you - This is, of course, to be understood in a moral sense; meaning that they should put away their sins. Sin is represented in the Scriptures as defiling or polluting the soul Ezekiel 20:31; Ezekiel 23:30; Hosea 5:8; Hosea 9:4; and the removal of it is represented by the act of washing; Psalms 51:2 : ‘Wash me thoroughly from mine iniquity, and cleanse me from my sin;’ Jeremiah 4:14 : ‘O Jerusalem, wash thine heart from wickedness, that thou mayest be saved;’ Job 9:30; 1 Corinthians 6:11; Hebrews 10:22; 2 Peter 2:22; Revelation 1:5; Revelation 7:14. It is used here in close connection with the previous verse, where the prophet says that their hands were flied with blood. He now…”

“Wash - Cleanse your hearts and hands. Isaiah 1:17”

“1:16 Wash . . . and be clean! The people were defiled by their sin and the uncleanness of their sacrifices. To be clean in God’s eyes, they needed to change their behavior, get rid of their sins, and give up their evil ways (see also 1:18).”

“Wash: Job 11:13, Job 11:14; Psa 26:6; Jer 4:14; Act 22:16; Co2 7:1; Jam 4:8; Rev 7:14 put away: Isa 55:6, Isa 55:7; Eze 18:30, Eze 18:31; Zac 1:3, Zac 1:4; Mat 3:8; Eph 4:22-24; Tit 2:11-14; Pe1 2:1 cease: Psa 34:14, Psa 37:27; Amo 5:15; Rom 12:9; Eph 4:25-29; Pe1 3:11 Isaiah 1:17”

“The first three run thus: "Wash, clean yourselves; put away the badness of your doings from the range of my eyes; cease to do evil." This is not only an advance from figurative language to the most literal, but there is also an advance in what is said. The first admonition requires, primarily and above all, purification from the sins committed, by means of forgiveness sought for and obtained. Wash: rachatzu, from râchatz, in the frequent middle sense of washing one's self. Clean yourselves: hizdaccu, with the tone upon the last syllable, is not the niphal of zâkak, as the first plur. imper. niph. of such verbs has generally and naturally the tone upon the penultimate (see Isa 52:11; Num…”