Albert Barnes Commentary Jeremiah 47:3

"At the noise of the stamping of the hoofs of his strong ones, at the rushing of his chariots, at the rumbling of his wheels, the fathers look not back to their children for feebleness of hands;" — Jeremiah 47:3 (ASV)

His strong horses - War-horses, chargers.

The rushing of his chariots - Rather, the rattling, the crashing noise which they make as they advance.

For feebleness of hands - The Philistines flee in such panic that a father would not even turn round to see whether his sons were effecting their escape or not.