Rabbi Elazar ben Azaryah taught that God split the Red Sea for the Israelites in the merit of their forefather Abraham. His proof comes from a sweeping passage in (Psalms 105:42-43): "For He remembered His holy word to Abraham His servant. And He led out His people with joy."
The psalm draws a direct line from God's covenant with Abraham to the Exodus from Egypt. God did not free the Israelites because they had earned it through their own righteousness. They had been slaves in Egypt for generations, and the rabbis acknowledged that many had sunk into Egyptian idolatry. What triggered the redemption was something far older: a promise God had made to Abraham centuries earlier.
Rabbi Elazar ben Azaryah's teaching belongs to a broader rabbinic discussion recorded in the Mekhilta about the reason for the splitting of the sea. Different sages attributed the miracle to different merits. Some credited Moses, others the faith of the people, others the merit of Jacob or Joseph. Rabbi Elazar ben Azaryah insisted that the credit belonged to Abraham and the covenant God had sealed with him.
The choice of Psalms 105 as the proof-text is significant. The psalm recounts the entire sweep of Israelite history, from Abraham to the conquest of the land, as a single story driven by one engine: God's faithfulness to a promise. "He remembered His holy word." The splitting of the sea was not a spontaneous miracle or a response to Israel's desperate prayers. It was the fulfillment of an oath God had sworn to one man, generations before his descendants ever set foot in Egypt.