The nations were drowned in the pit that Esau made. This refers to Pharaoh. In this net they hid, this refers to Sisera. Their foot was caught, this refers to Sennacherib.
The Lord is known for His righteous deeds. He demonstrated His judgment during the judgment He executed against Egypt, as it is said: "And Egypt shall know that I am the Lord" (Exodus 7:5). In practice, the wicked, like Pharaoh, struggle with their own hands. As for us, what can we say? Let us contemplate this. Selah. Then Moses and the Israelites sang this song to the Lord (Exodus 15:1).