John Trapp on Isaiah 6:7

Ver. 7. And he laid it upon my mouth] Not to burn him (for all this was viſional) but to expiate and purifie his lips by the Spirit of judgement and of burning, Chap. 4.4. to fire him up to an holy contention in godlineſs, and to fit him yet further for his Office, as the Apoſtles were for theirs by cloven tongues of fire, Act. 2.

And ſaid, Lo this hath touched thy lips] To the ſign words are uſed to make a perfect Sacrament. And here the cautelouſneſs of the Angel is to be noted: He ſaith not I have touched, 1 Cor. 15.10. but lo this coal hath touched thy lips. So Paul, yet not I, but the Grace of God in me. So the good and faithful ſervant, Not I, but thy Talent hath gained five Talents, Luk. 19.16. The Seraph was himſelf a burning creature as his very name importeth: howbeit it was not the Seraph but the Retheph or burning-coal that did the deed, that God might have all the glory.

Thine iniquity is taken away] Sacraments take not away ſin: but only teſtifie that iniquity is purged by Chriſt alone, who hath merited Juſtification and Sanctification.