Parashas Acharei Mos · Passuk 18:22
Chabad.org — English translation + Rashi
Torah Temima points to Sanhedrin 55a / Nedarim 51a.
English: Even partial contact with a male incurs liability; “to’evah” is expounded by Bar Kappara as “you go astray in it.”
Partial act + meaning of to’evah
Liability begins with ha’ara’ah; the term to’evah is read as a moral characterization of the act.