What is the ruling on searching for ancient artifacts on land owned by another, while giving one-fifth [of the finds in charity] and giving the landowner half of the remainder, especially if the owner refuses to grant permission?

It is not permissible to exploit another person's land by digging and searching for treasures or anything else, except with the owner's permission. The landowner's statement: "There is nothing in this land, my son, I don't want you to toil in vain," is not considered explicit permission. Therefore, clear permission must be sought from him.