'Solemnly' in the Bible

Moses took the bones of Joseph with him, for he had made the sons of Israel solemnly swear, saying, “God will surely take care of you, and you shall carry my bones from here with you.”

The Lord said to Moses, "Go down and solemnly warn the people, lest they force their way through to the Lord to look, and many of them perish.

Moses said to the Lord, "The people are not able to come up to Mount Sinai, because you solemnly warned us, 'Set boundaries for the mountain and set it apart.'"