I Samuel 6:3

3 They answered, "If you return the ark of the god of Israel, do not send it back to him without a gift; by all means send a guilt offering to him. Then you will be healed, and you will know why his hand has not been lifted from you."

3 And they said, If ye send away the ark of the God of Israel, send it not empty; but by all means return him a trespass-offering: then ye shall be healed, and it shall be known to you why his hand is not removed from you.