"Those who delight in truth sleep peacefully, with clear minds. The wise always take pleasure in truth expounded by the noble." (Translation by Thomas Cleary)
First, one has to know what the truth is, which is the difficult part. Most of us think we know what the truth is, but we do not know what the ultimate truth is. Those who are enlightened have realized this truth. If you are wise, the truth spoken by an enlightened person will bring you pleasure.