Albert Barnes Commentary Deuteronomy 6:4

"Hear, O Israel: Jehovah our God is one Jehovah:" — Deuteronomy 6:4 (ASV)

These words form the beginning of what is called the “Shema” (“Hear”) in the Jewish Services, and belong to the daily morning and evening service. They may be called “the creed of the Jews.”

This weighty text contains far more than a mere declaration of the unity of God in contrast to polytheism, or of the sole authority of the revelation that He had made to Israel in contrast to other supposed manifestations of His will and attributes. It asserts that the Lord God of Israel is absolutely God, and no other. He, and He alone, is Jehovah (Yahweh) the absolute, uncaused God; the One who had, by His election of them, made Himself known to Israel.