For thus saith the Lord GOD, the Holy One of Israel; In returning and rest shall ye be saved; in quietness and in confidence shall be your strength: and ye would not. But ye said, No; for we will flee upon horses; therefore shall ye flee: and, We will ride upon the swift; therefore shall they that pursue you be swift. One thousand shall flee at the rebuke of one; at the rebuke of five shall ye flee: till ye be left as a beacon upon the top of a mountain, and as an ensign on an hill.
God had been saying to Judah that their salvation laid in returning to Him. They thought that it depended on trusting in Egypt. God wanted them to understand that though it looked like Egypt would protect them but in reality, both Egypt and Judah would retreat in panic and be defeated in the end.