יִזְבְּח֗וּ לַשֵּׁדִים֙ לֹ֣א אֱלֹ֔הַ אֱלֹהִ֖ים לֹ֣א יְדָע֑וּם חֲדָשִׁים֙ מִקָּרֹ֣ב בָּ֔אוּ לֹ֥א שְׂעָר֖וּם אֲבֹתֵיכֶֽם׃
They sacrificed unto demons, no-gods, Gods that they knew not, New gods that came up of late, Which your fathers dreaded not.
Rashi on Deuteronomy
לא אלה — Understand this as the Targum does: They sacrifice unto devils in which is no utility, for if there were at least any utility in them to the world (as e.g:, the sun, moon and stars) God’s jealousy would not have been so intense (lit. — doubled) as it is now. (Sifrei Devarim 318:13).
Ramban on Deuteronomy
THEY SACRIFICED UNTO THE DEMONS, NO-GODS. I have [already] explained this.64Leviticus 17:7 (Vol. III, pp. 235-237).
Sforno on Deuteronomy
לשדים לא אלוה, forces which are not enduring; our sages in Chagigah 16 already taught us that these demons known as שדים are as mortal as is man himself.