R. Eliezer b. Yaakov says: Whence is it derived that a portico is not built in the azarah (the Temple court)? From "any tree (i.e., wood) beside the altar of the L-rd your G-d." "that you make for yourself": to include (in the interdict planting a tree beside) a bamah (a temporary altar).
(Devarim 16:22) "And you shall not set up for yourself a monument (matzeivah), which the L-rd your G-d hates": This tells me only of a matzeivah. Whence do I derive (the same for) an asheirah and idolatrous images? It follows, viz.: If a matzeivah, which was "loved" for the fathers, is "hated" for the sons, then an asheirah and idolatrous images, which were "hated" for the fathers, how much more so are they hated for the sons!