John Gill Commentary Deuteronomy 5:16

"Honor thy father and thy mother, as Jehovah thy God commanded thee; that thy days may be long, and that it may go well with thee, in the land which Jehovah thy God giveth thee." — Deuteronomy 5:16 (ASV)

Honour your father and your mother, as the Lord your God has
commanded you
And is the first commandment with promise, as the apostle observes, (Ephesians 6:2Ephesians 6:3) with a promise of long life and happiness in the land of Canaan, as follows:

that your days may be prolonged ;
see (Exodus 20:12) here it is added,

and that it may go well with you ;
and which the apostle also has in the place referred to:

in the land which the Lord your God gives you ;
the land of Canaan; which the same apostle explains to a greater latitude,

that you may live long on the earth ;
applying it to Christians under the Gospel dispensation, whether Jews or Gentiles.