12 He will take a censer full of burning coals from the Altar before God and two handfuls of finely ground aromatic incense and bring them inside the curtain and 13 put the incense on the fire before God; the smoke of the incense will cover the Atonement-Cover which is over The Testimony so that he doesn't die.
Matthew Henry's Commentary on Leviticus 16:12-13
Commentary on Leviticus 16:1-14
(Read Leviticus 16:1-14)
Without entering into particulars of the sacrifices on the great day of atonement, we may notice that it was to be a statute for ever, till that dispensation be at an end. As long as we are continually sinning, we continually need the atonement. The law of afflicting our souls for sin, is a statue which will continue in force till we arrive where all tears, even those of repentance, will be wiped from our eyes. The apostle observes it as a proof that the sacrifices could not take away sin, and cleanse the conscience from it, that in them there was a remembrance made of sin every year, upon the day of atonement, Hebrews 10:1,3. The repeating the sacrifices, showed there was in them but a feeble effort toward making atonement; this could be done only by offering up the body of Christ once for all; and that sacrifice needed not to be repeated.