וַֽיהוָ֞ה הֶאֱמִֽירְךָ֣ הַיּ֗וֹם לִהְי֥וֹת לוֹ֙ לְעַ֣ם סְגֻלָּ֔ה כַּאֲשֶׁ֖ר דִּבֶּר־לָ֑ךְ וְלִשְׁמֹ֖ר כָּל־מִצְוֺתָֽיו׃
Wiekuisty téż przyobiecał ci dzisiaj, że mu będziesz ludem wyłącznym, jako powiedział tobie, jeżelibyś przestrzegał wszystkich przykazań Jego;
Rashi
כאשר דבר לך AS HE HATH PROMISED THEE — in the words (Exodus 19:5) “Ye shall be a select portion unto Me” (Mekhilta).
Ramban
AND THE ETERNAL HATH AVOUCHED THEE. For this day is to you as the day of [the Revelation on] Sinai, and G-d exalted and magnified you by your acceptance of the Torah in order that you be His own treasure from among all peoples,44Exodus 19:5. and that thou shouldest keep all His commandments,45In Verse 18 before us. for, to you alone He gave His Torah and commanded you with all the commandments that are desireable before Him and to no other nation. It is similar to what is written, He declareth His word unto Jacob, His statutes and His ordinances unto Israel. He hath not dealt so with any nation.46Psalms 147:19-20.
Rashbam
He also האמירך, contributed His part in your becoming willing to become His people (and all that this entails). Moses refers to all the miracles G’d had performed for this people before they agreed to become His people.