Contradiction with Ecclesiastes 7:3
This verse suggests that "sorrow is better than laughter," which contradicts Philippians 2:18's call for rejoicing and joy.
Ecclesiastes 7:3: Sorrow [is] better than laughter: for by the sadness of the countenance the heart is made better. [Sorrow: or, Anger]
Contradiction with James 4:9
This verse advises to "be afflicted, and mourn, and weep" which opposes the notion of joy and rejoicing in Philippians 2:18.
James 4:9: Be afflicted, and mourn, and weep: let your laughter be turned to mourning, and [your] joy to heaviness.
Contradiction with Proverbs 14:13
The verse states "even in laughter the heart is sorrowful; and the end of that mirth is heaviness," contradicting the encouragement to rejoice in Philippians 2:18.
Proverbs 14:13: Even in laughter the heart is sorrowful; and the end of that mirth [is] heaviness.
Contradiction with Matthew 5:4
"Blessed are they that mourn" suggests a blessed state in mourning, which can be seen as contrary to the exhortation to rejoice in Philippians 2:18.
Matthew 5:4: Blessed [are] they that mourn: for they shall be comforted.