Deuteronomy 32:41
If I whet my glittering sword, and mine hand take hold on judgment; I will render vengeance to mine enemies, and will reward them that hate me. If I whet my glittering sword, and mine hand take hold on judgment; I will render vengeance to mine enemies, and will reward them that hate me.
The verse belongs to a song that recounts God's dealings with His people, including Israel's rebellion and its coming punishment. In that setting it affirms that vengeance and recompense belong to God. The song also looks ahead to future events, including the final victory of the faithful when Christ comes again in power and glory.
It declares that God takes judgment into His own hand and wields the sword that executes justice, for He will punish His enemies and repay those who hate Him. This taking of judgment is the act of the eternal God who lives forever. The declaration leads into the promise that He will avenge His servants and show mercy to His people.
Because God is ever ready to defend all who suffer unjustly and spreads His hand over His servants as a protective shield, no one can wound His chosen without wounding the hand of the Lord. To harm them is therefore to strike against Him, and cherishing suspicion and jealousy against those the Lord loves is exceedingly sinful. He may long endure human perversity and leave an unjust course unpunished for a time, yet He will remember wrongs and punish them, for His hand bears the sword of justice with which He renders vengeance to His enemies.