John Gill Commentary Ezekiel 46:12

"And when the prince shall prepare a freewill-offering, a burnt-offering or peace-offerings as a freewill-offering unto Jehovah, one shall open for him the gate that looketh toward the east; and he shall prepare his burnt-offering and his peace-offerings, as he doth on the sabbath day: then he shall go forth; and after his going forth one shall shut the gate." — Ezekiel 46:12 (ASV)

Now when the prince shall prepare a voluntary
burnt offering, or peace offerings voluntarily to the Lord
That is, on week days, distinct from sabbath days, new moons, feasts, and solemnities, of which before; and seems to have respect to week day lectures, in distinction from the weekly and monthly stated times, for the ministry of the word and administration of the Lord's supper; in which lectures the principal thing insisted on must be the atoning sacrifice of Christ, and peace and reconciliation made by his blood; for the Gospel, which is to be preached in season and out of season, is the ministry of reconciliation, or the word preaching peace by Jesus Christ; and which should at all times be held forth, to the faith of God's people; which is meant by the preparation of these offerings: and being voluntary ones show not only that Christ's sacrifice was a willing one, and offered without any reluctance, with all readiness and cheerfulness; but also that week day lectures are voluntary things, which men are not under necessary obligation to attend to, either ministers or people, but is a matter of free choice, as their circumstances will admit; and yet are acceptable to God, and agreeable to the will of Christ, the Prince, said to prepare these free will offerings:

one shall then open him the gate that looketh toward the east :
the place where he stood and worshipped on the sabbath day; on the evening of which it was shut, and remained so the six days of the week (Ezekiel 46:1, Ezekiel 46:2). Only when it was the prince's pleasure to offer a sacrifice, or to have the word preached, it was opened by one of the porters of the gates; or there was an open exercise of the ministry of the word, by one of the preachers of it:

and he shall prepare his burnt offerings, and his peace offerings, as
he did on the sabbath day ;
the same doctrine, respecting the sacrifice and satisfaction of Christ, must be delivered at such times, as he did on the sabbath day;

then he shall go forth; and after his going forth one shall shut the
gate ;
on the sabbath day, or the Lord's day, it was not to be shut till the evening, because that day is wholly to be devoted to the service of God; men are not to find their own ways, nor do their own work, nor seek their own pleasure; but on week days, when the lecture is over, the gate is shut immediately, and persons may return to their worldly business directly.