Contradiction with Proverbs 17:22
A merry heart does good like a medicine, but Ecclesiastes 5:17 describes a life of darkness, sorrow, and wrath.
Proverbs 17:22: A merry heart doeth good [like] a medicine: but a broken spirit drieth the bones. [like: or, to]
Contradiction with Philippians 4:4
Paul instructs to rejoice always in the Lord, whereas Ecclesiastes 5:17 mentions living in sorrow and wrath.
Philippians 4:4: Rejoice in the Lord alway: [and] again I say, Rejoice.
Contradiction with Psalm 30:11
God turns mourning into dancing, while Ecclesiastes 5:17 focuses on a life of grief and wrath.
Psalm 30:11: Thou hast turned for me my mourning into dancing: thou hast put off my sackcloth, and girded me with gladness;
Contradiction with John 16:22
Jesus promises that joy cannot be taken away, contrasting with a life of darkness and sorrow mentioned in Ecclesiastes 5:17.
John 16:22: And ye now therefore have sorrow: but I will see you again, and your heart shall rejoice, and your joy no man taketh from you.