Charles Ellicott Commentary 1 Samuel 5:4

"And when they arose early on the morrow morning, behold, Dagon was fallen upon his face to the ground before the ark of Jehovah; and the head of Dagon and both the palms of his hands [lay] cut off upon the threshold; only [the stump of] Dagon was left to him." — 1 Samuel 5:4 (ASV)

When they arose early on the morrow. —Strange to say, on the next day a new and startling circumstance aroused and disturbed the exultant Philistines. The idol had fallen again, but this time it was broken. No mere accident could account for what had happened. The head and hands were severed from the image and thrown contemptuously on the threshold of the temple, upon which every priest or worshipper must tread as they passed into the sacred house.

Only the stump of Dagon. —The Hebrew, rendered literally, reads, only Dagon was left to him: that is to say, only “the fish,” the least noble part of the idol image, was left standing; the human head and hands were tossed down for people to trample on as they entered; “only the form of a fish was left in him.”—R. D. Kimchi.