In 1 Samuel 20, the king is in the process of losing his mind, and his throne. Saul knows the truth - David is God’s chosen heir – but Saul still tries to deny it.
In his humanity, in an attempt to change reality, in his desire to stay in a place of prosperity, Saul takes matters into his own hands.
Tragically, we learn yet another lesson from the king; you can’t kill truth and keep God’s blessings.