Albert Barnes Commentary Luke 6:45

"The good man out of the good treasure of his heart bringeth forth that which is good; and the evil [man] out of the evil [treasure] bringeth forth that which is evil: for out of the abundance of the heart his mouth speaketh." — Luke 6:45 (ASV)

This verse is not found in the Sermon on the Mount as recorded by Matthew, but is recorded by him in Matthew 12:35. See Barnes on Matthew 12:35.