They sacrifice
zabach (zaw-bakh')
to slaughter an animal (usually in sacrifice) -- kill, offer, (do) sacrifice, slay.
upon the tops
ro'sh (roshe)
the head (as most easily shaken), whether literal or figurative (in many applications, of place, time, rank, itc.)
of the mountains
har (har)
a mountain or range of hills (sometimes used figuratively) -- hill (country), mount(-ain), promotion.
and burn incense
qatar (kaw-tar')
to smoke, i.e. turn into fragrance by fire (especially as an act of worship) -- burn (incense, sacrifice) (upon), (altar for) incense, kindle, offer (incense, a sacrifice).
upon the hills
gib`ah (ghib-aw')
a hillock -- hill, little hill.
under oaks
'allown (al-lone')
oak.
and poplars
libneh (lib-neh')
some sort of whitish tree, perhaps the storax -- poplar.
and elms
'elah (ay-law')
an oak or other strong tree -- elm, oak, teil-tree.
because the shadow
tsel (tsale)
shade, whether literal or figurative -- defence, shade(-ow).
thereof is good
towb (tobe)
good (as an adjective) in the widest sense; used likewise as a noun
therefore your daughters
bath (bath)
apple (of the eye), branch, company, daughter, first, old, owl, town, village.
shall commit whoredom
zanah (zaw-naw')
to commit adultery; figuratively, to commit idolatry (the Jewish people being regarded as the spouse of Jehovah)
and your spouses
kallah (kal-law')
a bride (as if perfect); hence, a son's wife -- bride, daughter-in-law, spouse.
shall commit adultery
na'aph (naw-af')
to commit adultery; figuratively, to apostatize -- adulterer(-ess), commit(-ing) adultery, woman that breaketh wedlock.