Leviticus 16:21

And Aharon shall lay his hands (upon him) in this order, his right hand upon his left, upon the head of the living goat, and confess over him all the iniquities of the children of Israel, and all their rebellions, and all their sins, and shall put them, with an oath uttered and expressed with the Great and glorious Name, upon the head of the goat, and send (him) away by the hand of a man prepared from the year foregoing, to take him into a rocky desert which is Beth-hadurey;

he will put them After they depart from Israel, it is as if they are given over onto the head of the goat, and they go to a place where they will never more be noticed. Scripture speaks this way so that everyone can understand it.

designated [literally: for the moment] someone who had been prepared for this moment (or, someone accustomed to go at any moment on Yom Kippur). The yod forms an adjective from the noun “moment”, as in the adjective “inner” [I Kings 6:27]. Those people who translate the word as “well-informed” are wrong, in my opinion. Our Sages, whose words are true, said [Yoma 66a] that this person was a kohen.

AND HE SHALL PUT THEM UPON THE HEAD OF THE GOAT. Such an expression is not used with reference to the bullock of Aaron [over which he confessed his own sins and those of the other priests], nor in relation to the goat of the sin-offering of the Eternal, nor regarding the leaning of hands upon any of the offerings. This is because all offerings were brought for acceptance upon the fires of G-d [which burnt on the altar], and thus they effected pardon and atonement. But this [goat that was sent away to Azazel], since it was not for G-d, and the recipient thereof [i.e. Sammael] has no power to offer atonement or pardon, therefore the goat merely carries the people’s sins away, and [the accusing angel] must answer “Amen” against his will. When the Israelites are free from all sins and transgressions [as after the moment of confession of sins over the goat sent to Azazel], he indeed carries their sins away, as is mentioned in many verses in the Torah (Deuteronomy 11:29). and the prophets. This then is [the meaning of the expression], and the goat shall bear upon him all their iniquities. That was the reason why the thread of crimson wool, 67a). There was also a thread of crimson wool tied to the door of the Sanctuary (ibid., 68 b). At the moment of the fulfillment of the Divine command concerning this goat, the threads miraculously turned white as a sign of the Divine forgiveness, as it is said, though your sins be as scarlet, they shall be as white as snow (Isaiah 1:18) (Yoma 68 b). turned white at the time when the goat was sent away to Azazel, i.e., at the moment that he pushed it over the cliff, when it was broken in pieces, as is mentioned in the words of the Sages., 67 a.

ביד איש עתי, a man familiar with the paths and the desert regions, someone always available, on call, for such an assignment.