Purity of heart means undivided loyalty to God — not performing goodness on the outside while harbouring wrong motives inside. The reward is the greatest imaginable: to see God face to face.
Memory phrase: Pure heart — see God
Talk about it: What is the difference between doing something kind to show off and doing it because you truly care?
Prayer: God, make my heart clean and honest. I don't want to hide anything from You.