Radak: This is like "Zibach Amon" (Divrei ha'Yamim II, 33:22), "Lecha Ezbach" (Tehilim 116:17). It is Po'el Yotzei (it acts on others; he offers a Korban). This tense is used to show that he does so often.

Radak citing Ibn Ezra: It is Po'el Yotzei Shelishi ¹ (he causes someone else to offer a Korban).

Radak: Idolaters used to offer there ? "Al he'Harim ha'Ramim v'Al ha'Geva'os v'Sachas Kol Etz Ra'anan" (Devarim 12:2).

Malbim: There they were Mezanah from under their G-d. The primary service of idolatry was Shechitah ? it was done among multitudes. Burning was a primary Avodah ? everyone did so by himself on hills below the mountains, under Alon and Livnah trees. Zenus was connected with idolatry. There was open Zenus on mountains, and covert Zenus on hills.

Rashi: It is oak; it grows acorns (gallnuts). Radak ? it has many branches, therefore they serve idolatry under it due to its shade ? "Ki Tov Tzilah."

Rashi: It is an elm tree. It has many branches; people plant it for shade. Radak ? its logs are Lavan (white).

Rashi: Because you connect to idolatry, like the rites of early Goyim, and they join with you. You intermarried with them, and your daughters born from the Nochrim's daughters, they conduct like their mothers, and they are Mezanah. So Yonason translates.

Radak: Because people of the house go outside the city to the tall mountains and under every fresh tree, there is place for daughters and daughters-in-law to be Mezanah.

Malbim: This is like their fathers.

Malbim: The custom was to send daughters outside to [the place of] their husbands, and daughters-in-law were in their [father-in-law's] house like it says in Shoftim (12:9; Avtzan sent 30 daughters, and brought 30 girls for his sons). Zenus implies under her husband; she is considered a Zonah. It says Tena'afnah about the daughters-in-law, for they were in their [father-in-law's] houses, where they openly permitted Zenus ¹ ! Therefore, they did not consider it Zenus, rather, mere Ni'uf, which includes also Bi'ah with a single girl ² .

The verse discusses girls in your house. Your daughters are single, so their Bi'ah is mere Zenus; your daughters-in-law are married, so their Bi'ah is Ni'uf! (PF) Refer to 4:13:6:1**.