Komentarz do Powtórzonego Prawa 27:18

משגה עור [CURSED BE] HE THAT CAUSES THE BLIND TO GO ASTRAY — This means: one who is blind (inexperienced) in a matter and one gives him bad advice (cf. Rashi on Leviticus 19:14).

Blind concerning a particular matter, and he offers ill advice. We derive [our case of one who] misleads from misleads [i.e., the case of not putting a stumbling block before the blind] in parshas Kedoshim. And from where we derive that case itself? See parshas Kedoshim (Vayikra 19:14).