John Gill Commentary Deuteronomy 27:16

"Cursed be he that setteth light by his father or his mother. And all the people shall say, Amen." — Deuteronomy 27:16 (ASV)

Cursed [be] he that sets light by his father, or his
mother
That secretly despises them in his heart, and by looks and gestures mocks at them in a private manner, unseen by others, (Proverbs 30:17) ; for if he publicly cursed them, that was cognizable by the civil magistrate, and he was to be put to death, (Leviticus 20:9) .

This follows next, as in the order of the ten commands, to that which respects the fear and worship of God; honouring parents being next to the glorifying of God, the Father of all:

and all the people shall say Amen ;
applaud the righteous sentence, saying, "so let it be".