Commentaries:
What vile things these people were committing on God's holy Sabbath days! They worshipped idols, sacrificed their children, even burning them in the fire, and afterward, they presented themselves at the Temple services. That is horrifying! God specifically mentions that they did these things on the Sabbath—on His day. It shows how far idolatry will take a person, imposing its will on the actions of an individual.
We need to be very careful about this. These people were guilty of the common Israelitish sin of idolatry—syncretism, the blending of the world's way with God's way. God, of course, does not accept it as true worship. How could He? The Israelites would attend services, supposedly in honor and out of respect for the Creator God after killing their children in the fires of Molech!
In Ezekiel 20-23, where a brief overview of the relationship between God and Israel is presented, idolatry and profaning the Sabbath are specifically named nine times as the major reasons God drove Israel into captivity.
John W. Ritenbaugh
Sabbathkeeping (Part 1)