Contradiction with Psalms 146:3
Daniel 6:28 indicates prosperity under a ruler, whereas Psalms 146:3 advises not to put trust in princes.
Psalms 146:3: Put not your trust in princes, [nor] in the son of man, in whom [there is] no help. [help: or, salvation]
Contradiction with Hosea 8:4
Daniel 6:28 describes favor during king's reigns; Hosea 8:4 mentions setting up kings without God's approval.
Hosea 8:4: They have set up kings, but not by me: they have made princes, and I knew [it] not: of their silver and their gold have they made them idols, that they may be cut off.
Contradiction with Jeremiah 17:5
Daniel 6:28 implies trust in earthly king's favor; Jeremiah 17:5 warns against trusting man over God.
Jeremiah 17:5: Thus saith the LORD; Cursed [be] the man that trusteth in man, and maketh flesh his arm, and whose heart departeth from the LORD.
Contradiction with Micah 7:5
Daniel 6:28 acknowledges royal dependency, whereas Micah 7:5 encourages not relying on close relationships, including rulers.
Micah 7:5: Trust ye not in a friend, put ye not confidence in a guide: keep the doors of thy mouth from her that lieth in thy bosom.
Contradiction with Isaiah 31:1
Daniel 6:28 shows prosperity through rulers, but Isaiah 31:1 warns against seeking help from earthly powers over God.
Isaiah 31:1: Woe to them that go down to Egypt for help; and stay on horses, and trust in chariots, because [they are] many; and in horsemen, because they are very strong; but they look not unto the Holy One of Israel, neither seek the LORD!