The declaration “Hear, O Israel, Yahweh our God is one Yahweh” (Deuteronomy 6:4). The name, Shema, comes from the first Hebrew word of the verse, shema, “hear.” Deuteronomy 6:4–9 contains all of this essential biblical truth. While several translations of verse 4 are grammatically correct, Jesus’s words in Mark 12:29 match the above translation best. Religious Jews pray the Shema three times a day as a devotion. No Sabbath worship occurs in the synagogue without it.
The Shema contains a key doctrinal truth and an obligation. The Shema demands that the hearers respond with their total being to this important revelation.
Regarding the nature of God, the word “one” (echad) means a compound unity, not an absolute singular. The medieval Jewish theologian Maimonides argued that God was yachid (an absolute singular). But, the Old Testament does not use this word to describe God. The word "echad" first occurs in Genesis 2:24, where a man and woman are made one (echad) in marriage. This is how Jesus could quote Deuteronomy 6:4 without denying his own deity.