When Saul sent messengers to take David, she said, He is sick.
Saul expected more loyalty from his daughter than he received. Jonathan had described David as Saul’s servant (1 Samuel 19:4), but Saul now called him his enemy (1 Samuel 19:17). Michal seems to have considered her lie justifiable (cf. 1 Samuel 19:11). Jonathan had not lied to Saul (1 Samuel 19:4-5). Both Jonathan and Michal’s words resulted in David’s safety temporarily, but Jonathan and Michal’s characters contrast in what they said to their father and king.