You can always tell the character of people by the way they treat those who they don't have to treat nice.
Saul was envious because he had slayed 1,000s and David his 10,000s. Littel did he know God arranged these things. Envy rises like the Sun. it's hot, seeking to heat everything in its path until all that is touched by it will soon look and feel the same.
We all share the Saul and david enmity everyday. Be careful, this rises like sun and can torch all things if not properly handled.
The same way david and saul had enmity is the very same way our character creeps over to the bad side.