Contradiction with Matthew 5:19
This verse suggests that breaking even the least commandments and teaching others to do so leads to being least in the kingdom of heaven, in contrast with the blessedness for keeping the Sabbath in Isaiah 56:2.
Matthew 5:19: Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach [them], the same shall be called great in the kingdom of heaven.
Contradiction with Colossians 2:16
This verse implies that no one should be judged regarding Sabbath days, contradicting the emphasis on keeping the Sabbath in Isaiah 56:2.
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 Galatians 4:9-10
This verse questions observing days and months, which can be seen as inconsistent with the emphasis on keeping the Sabbath in Isaiah 56:2.
Galatians 4:9-10: But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage? [turn ye again: or, turn ye back] [elements: or, rudiments]
Contradiction with Romans 14:5
Here, one person considers one day more sacred than another while another considers every day alike, suggesting a contradiction with the specific blessing for keeping the Sabbath in Isaiah 56:2.
Romans 14:5: One man esteemeth one day above another: another esteemeth every day [alike]. Let every man be fully persuaded in his own mind. [fully persuaded: or, fully assured]