John Gill Commentary Ezekiel 20:21

"But the children rebelled against me; they walked not in my statutes, neither kept mine ordinances to do them, which if a man do, he shall live in them; they profaned my sabbaths. Then I said I would pour out my wrath upon them, to accomplish my anger against them in the wilderness." — Ezekiel 20:21 (ASV)

Notwithstanding the children rebelled against me
After the death of their fathers, when they were come into the plains of Moab, and just going to enter the land; they rebelled against the Lord, and greatly provoked him, by joining themselves to Baalpeor, the idol of Moab, they worshipped, (Numbers 25:3) ;

they walked not in my statutes, neither kept my judgments to do them ;
they did as their fathers before them; though they saw with their eyes the judgments of God upon them, yet this did not deter them from following their evil ways:

which [if] a man do, he shall even live in them ;
(See Gill on Ezekiel 20:13);

they polluted my sabbaths ;
just as their fathers had done, taking no warning by them, and what befell them:

then I said, I would pour out my fury upon them, to accomplish mine
anger against them in the wilderness ;
twenty and four thousand died on account of the idolatry of Baalpeor, (Numbers 25:9) .