Then they said, "What shall be the trespass-offering which we shall return to him?" They said, "Five golden tumors, and five golden mice, [according to] the number of the lords of the Philistines; for one plague was on you all, and on your lords.
Yahweh had reduced the fertility of the crops of the Philistines as well as afflicting the people and their gods (1 Samuel 6:5). The Philistines remembered that this is what Yahweh had done to the Egyptians earlier (1 Samuel 6:6). The priests counseled the people not to harden their hearts as Pharaoh had done. Hardening the heart only brings divine retribution (cf. Joshua 7:19).