Contradiction with Matthew 6:16
This verse teaches not to appear unto men to fast, unlike Joel 1:13 which calls for public lamentation and fasting.
Matthew 6:16: Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.
Contradiction with Matthew 9:14-15
These verses describe Jesus explaining that his disciples do not fast while he is with them, which contrasts with the immediate call to fasting in Joel 1:13.
Matthew 9:14-15: Then came to him the disciples of John, saying, Why do we and the Pharisees fast oft, but thy disciples fast not?
Contradiction with Ecclesiastes 3:4
This verse says there is a time to laugh and dance, which is contrary to the call for mourning and lamentation in Joel 1:13.
Ecclesiastes 3:4: A time to weep, and a time to laugh; a time to mourn, and a time to dance;
Contradiction with Isaiah 61:3
Promises a spirit of praise instead of a spirit of despair, whereas Joel 1:13 urges putting on sackcloth and mourning.
Isaiah 61:3: To appoint unto them that mourn in Zion, to give unto them beauty for ashes, the oil of joy for mourning, the garment of praise for the spirit of heaviness; that they might be called trees of righteousness, the planting of the LORD, that he might be glorified.
Contradiction with Nehemiah 8:10
Encourages joy as strength, conflicting with the mourning and lamentation called for in Joel 1:13.
Nehemiah 8:10: Then he said unto them, Go your way, eat the fat, and drink the sweet, and send portions unto them for whom nothing is prepared: for [this] day [is] holy unto our Lord: neither be ye sorry; for the joy of the LORD is your strength.