Ezekiel 20:28

The prophet regards the worship on the high-places and under the evergreen trees as a Canaanitish usage adopted by Israel, as Deuteronomy 12. At the same time Israel usually employed the altars or chapels which they found for the service of Jehovah; but naturally many corruptions would creep into such service, and it might become little different from a service of Baal. In the oldest prophets, Amos and Hosea, it is the kindof worship at the high-places that is condemned, the revelry and heathenish merrymaking (Hosea 9:1) the sensuousness (Hosea 8:13; Amos 5:21), and the false conception Of deity implied in it (Hosea 6:6). The mere localities or multitude of altars do not seem assailed, except that the more there were of them the more sin was committed, because the whole worship was sinful (Hosea 8:11; Amos 4:4). Later this impure worship was perceived to be inseparable from the high-places and these themselves came under condemnation. Ezekiel does not go further in his condemnation of the high hills and green trees than his predecessor Jeremiah (Jeremiah 2:20; Jeremiah 3:6).

all the thick trees Evergreen and umbrageous trees appear to have been regarded as abodes of deity.

offered … their sacrifices Four words are employed: offerings of flesh, particularly the peace or thank-offerings; what is called their "offering" or oblation, a general word used of bloodless sacrifices as well as of others, possibly first-fruits and the like; their "sweet savour," usually said of the odour of the flesh or fat burnt upon the altar, but also of the odour of meal-offerings (ch. Ezekiel 16:19); and finally, drink-offerings. The clause "and there … provocation of their offering" is wanting in LXX. The term "offering" (Korban), found only in Lev., Numb., again in Ezekiel 40:43 (see there).