Contradiction with Proverbs 21:31
Ecclesiastes 9:14 implies unpredictability in battle outcomes, whereas Proverbs 21:31 suggests a prepared army leads to safety.
Proverbs 21:31: The horse [is] prepared against the day of battle: but safety [is] of the LORD. [safety: or, victory]
Contradiction with 2 Chronicles 20:15
Ecclesiastes 9:14 depicts human strategies shaping battle outcomes, but 2 Chronicles 20:15 states that victory belongs to God.
2 Chronicles 20:15: And he said, Hearken ye, all Judah, and ye inhabitants of Jerusalem, and thou king Jehoshaphat, Thus saith the LORD unto you, Be not afraid nor dismayed by reason of this great multitude; for the battle [is] not yours, but God's.
Contradiction with Psalms 33:16
Ecclesiastes 9:14 describes potential for small forces to win, while Psalms 33:16 claims no king is saved by the size of his army.
Psalms 33:16: There is no king saved by the multitude of an host: a mighty man is not delivered by much strength.
Contradiction with Isaiah 31:1
Ecclesiastes 9:14 involves reliance on human military strength; Isaiah 31:1 warns against trusting in chariots and horses 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!
Contradiction with 1 Samuel 17:47
Ecclesiastes 9:14 discusses human strategy for victory, but 1 Samuel 17:47 asserts that battles are won by God's power.
1 Samuel 17:47: And all this assembly shall know that the LORD saveth not with sword and spear: for the battle [is] the LORD'S, and he will give you into our hands.