Sforno on Leviticus 4:22/ספורנו על ויקרא ד׳:כ״ב

1אשר נשיא יחטא, when the King (or political head) sins; there is no conditional word אם, “if,” i.e. the Torah considers it as almost a given that the political head of the people will become guilty of at least an inadvertent sin. Moses describes such a likely scenario as the result of the people enjoying good times, when he says in Deuteronomy 32,15 וישמן ישורון ויבעט, “when Yeshurun waxed fat it kicked. ואשם, he realised himself that he had sinned; it did not have to be brought to his attention by others. או הודע לו, or his sin had to be brought to his attention by others. The vowel cholem on the letter vav substitutes for the vowel shuruk which would have made it clear that it is a passive mode.