Deuteronomy 11:13 says:
וְהָיָ֗ה אִם־שָׁמֹ֤עַ תִּשְׁמְעוּ֙ אֶל־מִצְוֺתַ֔י אֲשֶׁ֧ר אָנֹכִ֛י מְצַוֶּ֥ה אֶתְכֶ֖ם הַיּ֑וֹם לְאַהֲבָ֞ה אֶת־יְהוָ֤ה אֱלֹֽהֵיכֶם֙ וּלְעָבְד֔וֹ בְּכָל־לְבַבְכֶ֖ם וּבְכָל־נַפְשְׁכֶֽם׃
And it shall be that if you will listen to My commandments which I command you this day, to love the LORD your God, and to serve Him with all your heart and with all your soul.
The word וְהָיָ֗ה seems extra. The verses that follow make it seem quite obvious that if you obey the commandments, you will receive a reward. The reward comes in the future, after performing the commandments. What then, is the purpose of the word וְהָיָ֗ה in this verse?