*1 CORINTHIANS 13: 6*
Does not rejoice in unrighteousness (does not delight in evil). Unrighteousness comes from the word adikia - which means a deed violating law and justice.
The definition of unrighteous is: Not righteous; wicked - Not right or fair; unjust - morally bad or wrong - deliberately violating accepted principles of right and wrong.
But rejoices with the truth (righteousness). Since this is a spin off 'not rejoicing in unrighteousness', I'm going to take 'the truth' as the opposite of unrighteousness = righteousness. The truth comes from the word alētheia - which means that candour of mind which is free from affection, pretence, simulation, falsehood, deceit - the truth as taught in the Christian religion, respecting God and the execution of his purposes through Christ, and respecting the duties of man.
The definition of righteous is: Morally upright; without guilt or sin - concerned with principles of right and wrong or conforming to standards of behavior and character based on those principles.