'Eye' in the Bible

But keep an eye on it. If it should go up by the way of its own border to Beth Shemesh, then he has brought this great calamity on us. But if that is not the case, then we will know that it was not his hand that struck us; rather, it just happened to us by accident."

But Nahash the Ammonite said to them, "The only way I will make a treaty with you is if you let me gouge out the right eye of every one of you and in so doing humiliate all Israel!"

So Saul was keeping an eye on David from that day onward.