Charles Ellicott Commentary Ezekiel 20:27

"Therefore, son of man, speak unto the house of Israel, and say unto them, Thus saith the Lord Jehovah: In this moreover have your fathers blasphemed me, in that they have committed a trespass against me." — Ezekiel 20:27 (ASV)

Your fathers have blasphemed me. —The fourth period of Israelite history, though actually by far the longest, is very briefly passed over (Ezekiel 20:27–29). It includes the whole period of the settlement in Canaan, from the conquest to the prophet's own time, and was marked by the same characteristics as before. The particular way specified here in which they blasphemed was by the erection of idolatrous altars on every high place.