1 Samuel 5:4,5 - Joseph Benson’s Commentary on the Old and New Testaments

Behold Dagon was fallen &c. Which showed that his former fall was not by chance, but by the power of God, before whom he could not stand. The head of Dagon, and both his hands, were cut off The head is the seat of wisdom; the hands the instruments of action; both are cut off, to show that he had neither wisdom nor strength to defend himself or his worshippers. Thus the priests, by concealing Dagon's shame before, make it more evident and infamous. The stump Hebrew, only Dagon; that is, saith Rabbi Kimchi, that part of it from which it was called Dagon, namely, the fishy part; for dag, in Hebrew, signifies a fish. Upon it Upon the threshold; there the trunk abode in the place where it fell, but the head and hands were flung to distant places. Neither the priests tread on the threshold of Dagon Out of reverence to it, looking upon it as a holy thing, by the touch of Dagon's head and hands. So foolishly did they pervert the meaning of God, that instead of being convinced that Dagon was no god, they even honoured the threshold which his broken limbs had fallen upon! Unto this day When this history was written, which, if written by Samuel toward the end of his life, was a sufficient ground for this expression.