John Gill Commentary Deuteronomy 28:1

"And it shall come to pass, if thou shalt hearken diligently unto the voice of Jehovah thy God, to observe to do all his commandments which I command thee this day, that Jehovah thy God will set thee on high above all the nations of the earth:" — Deuteronomy 28:1 (ASV)

And it shall come to pass, if you shall listen diligently
unto the voice of the Lord your God
In his law, and by his prophets: to observe [and] to do all his commandments, which I command you this
day ;
for without observing them to do them, hearing them would be to little purpose, and they were all of them to be observed and done, the lesser and weightier matters of the law as they were commanded by Moses in the name of the Lord, and as they would be taught, explained, and enforced by the prophets: that the Lord your God will set you on high above all nations of the
earth :
as they were in the times of David and Solomon; (See Gill on Deuteronomy 26:19).