Saul heard that David was discovered, and the men who were with him: now Saul was sitting in Gibeah, under the tamarisk tree in Ramah, with his spear in his hand, and all his servants were standing about him.
"When Saul heard that David was discovered, and the men with him"  (1 Samuel 22:6).  This is a reference to David's having been publicly "discovered" as an enemy of the king and an outlaw in Israel.  There was no way that such information could have been hidden.  Saul himself had forced David to flee for his life; and David's family, most naturally, were also afraid.  Ruthless, savage tyrants of Saul's type frequently murdered whole families because of their hatred of any one of them.