“Rabbi Yehoshua ben Korchah said, Why does [the passage of] “Shema” precede [the passage of] “Vehayah im shamoa“? Only so one will first accept upon himself the yoke of Heaven’s sovereignty, and afterwards accept upon himself the yoke of the commandments.
The Shema section begins with the verse (Deuteronomy 6:4): Hear, O Israel, Hashem is our God, Hashem is the One and Only. This declaration affirms the existence and absolute unity of God, and constitutes a recognition and acceptance of His sovereignty.
Accepting God’s sovereignty logically precedes acceptance of His dictates. Only one who views himself as a subject of the King will obey His commands.” Yad Avraham [2.2], Seder Zeraim Vol. I, Berachoth Chapter Two: Hayah Korei – Artscroll Mishnah Series