What does 1 Samuel 18:17 mean?

Saul said to David, 'Here's my oldest daughter Merab. I'll give her to you as your wife if you keep fighting bravely for me and for the Lord. But Saul was thinking, 'I won't have to kill him myself. The Philistines will do it.' 1 Samuel 18:17 - Modern Text Bible

(Saul offers his daughter as a reward, but his real motive is to put David in more danger, hoping he'll be killed in battle.)