John Gill Commentary Deuteronomy 28:2

"and all these blessings shall come upon thee, and overtake thee, if thou shalt hearken unto the voice of Jehovah thy God." — Deuteronomy 28:2 (ASV)

And all these blessings shall come on you and overtake you ,
&c.] The blessings mentioned after, which should come upon them from God from heaven, by the direction of his providence, and that freely and plentifully, and beyond your expectations and deserts, and continue with them:

if you shall hearken to the voice of the Lord your God ;
obedience to the law being the condition of their coming and continuance; for only temporal blessings in the land of Canaan are here intended, as follow.