Charles Ellicott Commentary Numbers 12:11

"And Aaron said unto Moses, Oh, my lord, lay not, I pray thee, sin upon us, for that we have done foolishly, and for that we have sinned." — Numbers 12:11 (ASV)

Alas, my lord.— The word rendered alas! is an exclamation of entreaty rather than of lamentation. It is used towards superiors in conjunction with adoni (my lord) in Genesis 40:20; 1 Kings 3:17.

Lay not the sin upon us ... —Better, lay not sin (i.e., the punishment which is due to it) upon us, because (or, inasmuch as) we have done foolishly, etc. Aaron does not seek to shift the guilt which had been incurred from himself and Miriam to any others, but prays that they may not be constrained to bear the punishment which their sin had justly deserved. In Zechariah 14:19 the same word hattath is rendered punishment.