Adam Clarke on 1 Samuel 6:3

Send it not empty - As it appears ye have trespassed against him, send him an offering for this trespass.

Why his hand is not removed - The sense is, If you send him a trespass-offering, and ye be cured, then ye shall know why his judgments have not been taken away from you previously to this offering.

It is a common opinion, says Calmet, among all people, that although the Supreme Being needs nothing of his creatures, yet he requires that they should consecrate to him all that they have; for the same argument that proves his independence, infinitude, and self-sufficiency, proves our dependence, and the obligation we are under to acknowledge him by offering him due marks of our gratitude and submission. Such sentiments were common among all people; and God himself commands his people not to appear before him without an offering, Exo 23:15 : None shall appear before me empty.