David also arose afterward
 After Saul was gone: and went out of the cave;
 where he had been all the time that Saul had been in it: and cried after Saul:
 with a loud voice: my lord the king; by which titles Saul would know that he was called unto: and when Saul looked behind him;
 to see who it was that called unto him: David stooped with his face to the earth, and bowed himself:
 giving reverence and honour to him as a king; (See Gill on  1 Samuel 20:41).