Rashi on Deuteronomy 13:6/רש"י על דברים י״ג:ו׳

1סרה [BECAUSE HE HATH SPOKEN] סרה — i.e. something that is strange in the world (more lit., removed from the world), something which never existed and was never created (a pure invention), and which I never bade him say; detournure in O. F.

2והפדך מבית עבדים AND WHO RELEASED YOU OUT OF THE HOUSE OF SERVANTS — even though he had no other claim on you but that He delivered you, it would be sufficient for Him to claim your obedience (Sifrei Devarim 86:5).