1
על דבר. עַל הָעֵצָה שֶׁיָּעֲצוּ אֶתְכֶם לְהַחֲטִיאֲכֶם: על דבר may be translated BECAUSE OF THE WORD — i.e. because of the advice which they gave you in order to entice you into sin (Sifrei Devarim 250:1).
2
בדרך. כְּשֶׁהֱיִיתֶם בְּטֵרוּף (ספרי): בדרך IN THE WAY — when you were in a state of exhaustion (Sifrei Devarim 250:2).