Psalm 18:15

Then the channels of water were seen
Or, "of the sea"; as in ( 2 Samuel 22:16 ) . There seems to be an allusion to the drying up of the sea when the Israelites passed through it. Aben Ezra interprets this of the discovery of the secrets of enemies, and of their deep schemes and counsels, which they seek to hide, but are made known by him who sees all things in the dark; and so the following clause;

and the foundations of the world were discovered;
but it rather seems to intend the utter extirpation and ruin of the Jewish nation, both in their civil and ecclesiastic state, the foundation of which was rooted up and laid bare; unless with Jerom we understand this of the ministers of the word, in whom the doctrines of grace were channelled, and who were as fountains of water; and of the foundation of the apostles and prophets made known in the Gospel: but the former sense is best; since it follows,

at thy rebuke, O Lord; at the blast of the breath of thy nostrils;
for the destruction of the Jews was the effect of divine wrath and vengeance: so ends the account of the wonderful appearance of God in favour of the person the subject of this psalm, and against his enemies; the deliverance wrought for him is next described.