Rashi on Deuteronomy 32:15/רש"י על דברים ל״ב:ט״ו

1עבית has the meaning of “thickness” (stoutness), it therefore means: “ Thou hast waxed fat”.

2כשית is the same as כסית (‎ס and ש interchanging). It has the same meaning as in Job 15:27 “Because he hath covered (כסה) his face with his fatness”— like a person who is full of fat inside and whose flanks therefore lie in folds outside, as it goes on to state, (Job 15:27) “and be made folds of fat on his flanks” (Sifrei Devarim 318:6).

3כשית — There exists a Kal form (as is this word) in the sense of covering, as (Proverbs 12:16) “And a prudent man is covered with (וְכֹסָה) shame”. If it had written כִּשִּׂיתָ with a dagesh in the ש. it would imply, “Thou hast covered others (or other things)” (i.e., it would be transitive), as in the text already quoted, “For he hath covered (כִסָּה) his face”.

4וינבל צור ישעתו AND HE LIGHTLY ESTEEMED THE ROCK OF HIS SALVATION — This means, He showed contempt for Him and scorned Him, as it is said, (Ezekiel 8:16) “[and, behold, … there were … men] with their buttocks towards the Temple of the Lord” — surely, there can be no greater contempt than this (see Rashi on this verse) (Sifrei Devarim 318:9).