And he laid it upon my mouth, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.
He lain (it) upon my mouth, and said, Lo, this hath touched thy lips - (cf. note, Isaiah 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 (Acts 2:3-4) when they were being set apart to speak in various languages of Jesus.
And thine iniquity is taken away - implying conscious unworthiness of acting as God's messenger.
And thy sin purged ( tªkupaar (H3722)) - literally, covered (cf. note, Isaiah 4:5-6, "defense ... covert"); i:e., 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.