John Gill Commentary Deuteronomy 24:9

"Remember what Jehovah thy God did unto Miriam, by the way as ye came forth out of Egypt." — Deuteronomy 24:9 (ASV)

Remember what the Lord your God did unto Miriam
Who was stricken with leprosy for speaking against Moses, and was shut up seven days; and they are reminded of this instance, partly to warn them against entertaining evil suspicions, and surmises of persons in power and authority, and speaking evil of them; and partly to expect that punishment would certainly be inflicted on them, should they be guilty of the same crime; nor should they think it hard, either to be smitten with leprosy, or to be shut up for it; since Miriam, a prophetess, and the sister of Moses, was so used; and that when

by the way, after that you were come out of Egypt :
when upon their journey, and were retarded in it, and obliged to stay at least seven days before they could proceed on in it; see (Numbers 12:14–16) .