1 Samuel 20:25-26

25The king sat on his seat as on previous occasions, on his seat by the wall; then Jonathan stood up, and Abner [his commander] sat down by Saul’s side, but David’s place was empty.

26Yet Saul did not say anything that day, for he thought, “It is an incident [of some kind] and he is not [ceremonially] clean—surely he is unclean.”