'Solemnly' in the Bible

Rather it is because of his love for you and his faithfulness to the promise he solemnly vowed to your ancestors that the Lord brought you out with great power, redeeming you from the place of slavery, from the power of Pharaoh king of Egypt.

"I solemnly swear to heaven I say "As certainly as I'm alive and living forever,

he said to them, "Keep in mind all the words I am solemnly proclaiming to you today; you must command your children to observe carefully all the words of this law.