Contradiction with Psalm 121:3
While Isaiah 62:6 mentions watchmen who will not hold their peace day nor night, Psalm 121:3 implies that God does the watching, suggesting humans need not be restless guardians.
Psalm 121:3: He will not suffer thy foot to be moved: he that keepeth thee will not slumber.
Contradiction with Matthew 6:6
Isaiah speaks about constant public declarations, while Matthew encourages private, personal prayer.
Matthew 6:6: But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
Contradiction with Ecclesiastes 3:7
Contradicts continuous speaking in Isaiah 62:6 by stating there is "a time to keep silence."
Ecclesiastes 3:7: A time to rend, and a time to sew; a time to keep silence, and a time to speak;
Contradiction with Amos 5:13
Implies that the prudent should keep silence in times of evil, contradicting the constant vocal vigilance mentioned in Isaiah 62:6.
Amos 5:13: Therefore the prudent shall keep silence in that time; for it [is] an evil time.
Contradiction with Proverbs 17:28
Suggests that silence can be wise, contrasting the incessant proclamations commanded in Isaiah.
Proverbs 17:28: Even a fool, when he holdeth his peace, is counted wise: [and] he that shutteth his lips [is esteemed] a man of understanding.