רְאֵ֗ה אָנֹכִ֛י נֹתֵ֥ן לִפְנֵיכֶ֖ם הַיּ֑וֹם בְּרָכָ֖ה וּקְלָלָֽה׃
Behold, I set before you this day a blessing and a curse:
Noam Elimelech
Rashi on Deuteronomy
ראה אנכי ... ברכה וקללה BEHOLD I [SET BEFORE YOU THIS DAY] A BLESSING AND A CURSE — those which are later to be recited on Mount Gerizim and on Mount Ebal respectively (cf. v. 29).
Kli Yakar on Deuteronomy
Look, I place before you today. “See” is singular. “Before you” is plural. This is what our Sages teach us: A person must always view things as if the entire world is half righteous and half wicked. If he performs a single mitzvah he tips himself and the entire world to the side of merit. Therefore Moshe spoke to every individual, “See” that he should see in his thought that every single action affects all of them.