Contradiction with Amos 5:21
Numbers 6:18 describes a specific ritual in fulfilling a vow to God, while Amos 5:21 reflects God's rejection of Israel's rituals and offerings when devoid of justice and righteousness.
Amos 5:21: I hate, I despise your feast days, and I will not smell in your solemn assemblies. [in...: or, your holy days]
Contradiction with Psalm 40:6
Numbers 6:18 includes a ceremonial sacrifice; however, Psalm 40:6 emphasizes that God does not desire sacrifices as much as obedience and a righteous heart.
Psalm 40:6: Sacrifice and offering thou didst not desire; mine ears hast thou opened: burnt offering and sin offering hast thou not required. [opened: Heb. digged]
Contradiction with Isaiah 1:11
Numbers 6:18 involves a burnt offering, whereas Isaiah 1:11 illustrates God's displeasure with an abundance of sacrifices from a rebellious people.
Isaiah 1:11: To what purpose [is] the multitude of your sacrifices unto me? saith the LORD: I am full of the burnt offerings of rams, and the fat of fed beasts; and I delight not in the blood of bullocks, or of lambs, or of he goats. [he goats: Heb. great he goats]
Contradiction with Hosea 6:6
Numbers 6:18 details a sacrificial ritual, yet Hosea 6:6 highlights God's preference for mercy and knowledge of Him over burnt offerings.
Hosea 6:6: For I desired mercy, and not sacrifice; and the knowledge of God more than burnt offerings.
Contradiction with Proverbs 21:3
Numbers 6:18 involves ritual sacrifice, while Proverbs 21:3 states that doing justice and judgment is more acceptable to the Lord than sacrifice.
Proverbs 21:3: To do justice and judgment [is] more acceptable to the LORD than sacrifice.
Contradiction with 1 Samuel 15:22
Numbers 6:18 prescribes a sacrificial procedure, whereas 1 Samuel 15:22 underscores obedience to God as being more important than sacrificial offerings.
1 Samuel 15:22: And Samuel said, Hath the LORD [as great] delight in burnt offerings and sacrifices, as in obeying the voice of the LORD? Behold, to obey [is] better than sacrifice, [and] to hearken than the fat of rams.