A Dirham in the desert

A man passed by another digging in the desert. He said to him, "Where are you, man, and why are you digging in the desert?" He said: "I have buried in this desert some money, and I do not lead to his place," he said to him: "You should have made it a sign." He said: "I have done." He said: "What is the mark?" He said: "A cloud in the sky was the same, and I do not see the mark now."