C. F. Keil and Franz Delitzsch on Deuteronomy 12:2-3

Deu 12:2-3

Ye shall destroy all the places where the Canaanites worship their gods, upon the high mountains, upon the hills, and under every green tree (cf. Jer 2:20; Jer 3:6; Jer 17:2; 2Ki 16:4; 2Ki 17:10). The choice of mountains and hills for places of worship by most of the heathen nations, had its origin in the wide-spread belief, that men were nearer to the Deity and to heaven there. The green trees are connected with the holy groves, of which the heathen nations were so fond, and the shady gloom of which filled the soul with holy awe at the nearness of the Deity. In the absence of groves, they chose green trees with thick foliage (Eze 6:13; Eze 20:28), such as the vigorous oak, which attains a great age, the evergreen terebinth (Isa 1:29-30; Isa 57:5), and the poplar or osier, which continues green even in the heat of summer (Hos 4:13), and whose deep shade is adapted to dispose the mind to devotion.