What are "Imrei Kel"?
Radak: They are the Mitzvos that Hashem command people. All nations are commanded, not only Yisrael, just Yisrael received additional Mitzvos, and Hashem was Mekadesh their bodies and food. Mitzvos that intellect understands, also Adam ha'Rishon and his seed were commanded.
Why does it mention their sin?
Rashi: Punishments come on a person only due to his sin 1 .
Malbim: A second evil came on them after they were saved from the first, because they returned to eat their vomit (sin) and rebelled against Hashem's words.
Radak (10): Regarding those who traverse Midbaros or seas, it did not mention their sin, for they did not sin initially; there is no damage in their trip. Affliction and danger came later, so they will repent to Hashem.
What is "Atzas Elyon"?
Radak: It is what He counseled people to do and live in [those ways]. Those who rebel against them, Hashem afflicts them with illness or captivity.
Malbim: Hashem counseled to do a miracle for them [to save them from the first affliction] in order that they will return to Him and guard His Mitzvos; they did not do so.
