Contradiction with Matthew 7:1
Leviticus 13:21 involves judging skin conditions, while Matthew 7:1 advises not to judge others.
Matthew 7:1: Judge not, that ye be not judged.
Contradiction with James 2:4
Leviticus 13:21 requires differential treatment based on outward appearances, while James 2:4 warns against being partial and making distinctions among yourselves.
James 2:4: Are ye not then partial in yourselves, and are become judges of evil thoughts?
Contradiction with Colossians 2:16
Leviticus 13:21 prescribes specific rules and judgments, whereas Colossians 2:16 tells believers not to let others judge them by such religious observances.
Colossians 2:16: Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath [days]: [in meat...: or, for eating and drinking] [respect: or, part]
Contradiction with Romans 14:13
Leviticus 13:21 involves passing judgment on physical afflictions, whereas Romans 14:13 advises to stop judging one another.
Romans 14:13: Let us not therefore judge one another any more: but judge this rather, that no man put a stumblingblock or an occasion to fall in [his] brother's way.
Contradiction with 1 Samuel 16:7
Leviticus 13:21 emphasizes external observations for the affliction, while 1 Samuel 16:7 teaches that the Lord looks at the heart, not outward appearances.
1 Samuel 16:7: But the LORD said unto Samuel, Look not on his countenance, or on the height of his stature; because I have refused him: for [the LORD seeth] not as man seeth; for man looketh on the outward appearance, but the LORD looketh on the heart. [outward...: Heb. eyes]