פירוש על תהילים 18:8

The earth shook and quaked This is not connected to the preceding verse, but its beginning is connected to its end; i.e., when He was angered, the earth shook and quaked. [The word] כי is used as an expression of “when.” When He was angered and came to wreak the vengeance of His people, His servants, on Pharaoh and his people, the earth shook and quaked.