Charles Ellicott Commentary Deuteronomy 32:40-41

"For I lift up my hand to heaven, And say, As I live for ever, If I whet my glittering sword, And my hand take hold on judgment; I will render vengeance to mine adversaries, And will recompense them that hate me." — Deuteronomy 32:40-41 (ASV)

For I lift up my hand. —This is the form of taking an oath. The two verses may be connected as follows: “For I lift up my hand to heaven, and say, As I live for ever, if I whet my lightning sword, and my hand take hold on judgment, I will render vengeance to mine enemies, and repay them that hate me.”