ἔγνω δὲ φώρ τε φῶρα καὶ λύκος λύκον → the thief knows the thief and the wolf knows the wolf, and thief knows thief and wolf his fellow wolf, set a thief to catch a thief
[Seite 24] von Männern verlassen sein, Mangel an Männern haben, Strab. 6, 3, 3.