Charles H. Spurgeon on Psalms 74:14

Thou brakest the heads of leviathan, etc. It is spoken of Pharaoh's army which God destroyed in the Red Sea; that is, the destruction of the Egyptians was a pledge of the accomplishment of God's promise to cast the Canaanite out of the promised land, and to give them possession of it. Many hardships they were to pass through in the wilderness, but God gave them this mercy as food, not to their bodies, but food to their faith, while they were in the wilderness: therefore, those former great and glorious promises were accomplished. So that former mercies are food that God gives unto the faith of his people to feed upon, till he hath perfectly accomplished whatever he hath promised unto his church. William Strong.