Isaiah 6:7

“And he laid [it] upon my mouth, &c.] Because he had complained of the impurity of his lips, and that his mouth might take in by faith this comfortable doctrine of pardon, and it might be filled with praise and thankfulness; it denotes the ministration of the Gospel, as a means of the application of pardoning grace: and said, lo, this hath touched thy lips; this coal, as a symbol of the word; the particle “lo”, or “behold”, is prefixed to this declaration, as requiring attention to a matter of importance, and as expressing something wonderful, and declaring something sure and certain; all which the pardon of sin is, and which is spoken of without a figure in the next words: and thine iniquity…”

“mouth . . . lips--(See on Isa 6:5). The mouth was touched because it was the part to be used by the prophet when inaugurated. So "tongues of fire" rested on the disciples (Act 2:3-4) when they were being set apart to speak in various languages of Jesus. iniquity--conscious unworthiness of acting as God's messenger. purged--literally, "covered," that is, expiated, not by any physical effect of fire to cleanse from sin, but in relation to the altar sacrifices, of which Messiah, who here commissions Isaiah, was in His death to be the antitype: it is implied hereby that it is only by sacrifice sin can be pardoned.”

“And he laid it upon my mouth - Margin, ‘And he caused it to touch my mouth.’ This is the more correct rendering. It was a slight, momentary touch, sufficient merely to be a “sign or token” that he was cleansed. Thine iniquity is taken away - That is, whatever obstacle there existed to your communicating the message of God to this people, arising from your own consciousness of unworthiness, is taken away. You are commissioned to bear that message, and your own consciousness of guilt should not be a hinderance. To understand this, it should be remembered that “fire,” among the orientals, has been always regarded as an emblem of “purifying.” Thus the Sabeans, the followers or Zoroaster in…”

“Laid it - So as only to touch my lips, and not to burn them; which God could easily effect. Lo - This is a sign that I have pardoned and purged the uncleanness of thy lips. Isaiah 6:8”

“6:7 your guilt is removed, and your sins are forgiven: The prophet’s experience of forgiveness anticipated Israel’s national need for forgiveness and cleansing (43:25; 44:22; see study note on 39:6-7).”

“he laid it upon: Heb. caused it to touch, Jer 1:9; Dan 10:16 thine iniquity: Isa 43:25, Isa 53:5, Isa 53:10; Mat 9:2; Heb 9:13, Heb 9:14; Jo1 1:7, Jo1 2:1, Jo1 2:2 Isaiah 6:8”