"I shall sing to the Lord," for He is merciful. The Mekhilta turns from God's power and wisdom to the attribute that defines the Jewish understanding of the divine character more than any other: mercy. The Israelites at the Red Sea did not only witness destruction. They witnessed salvation — and salvation is an expression of mercy.
The proof texts assemble the full portrait. First, the revelation at Sinai where God proclaimed His own nature: "Hashem, Hashem, the God who is merciful and gracious" (Exodus 34:6). This is the foundational self-description — when God chose to define Himself, mercy came first. Then Moses' reassurance to the next generation: "For a merciful God is the Lord your God" (Deuteronomy 4:31). The mercy is not occasional. It is constitutional. God is merciful the way fire is hot — it is His essential nature.
David added his own testimony: "Remember Your mercies, Hashem" (Psalms 25:6) and "Good is the Lord to all, and His mercies are on all His works" (Psalms 145:9). The scope of God's mercy extends beyond Israel to all of creation. Even the destruction of the Egyptians at the sea was bounded by mercy — tradition teaches that the angels were silenced from singing because God grieved over the drowning Egyptians. Finally, Daniel declares: "To the Lord our God is mercy and forgiveness" (Daniel 9:9). The Mekhilta weaves these verses into a single declaration: the God who split the sea is, above all else, the God who shows mercy.