'Solemnly' in the Bible

and said, "'I solemnly swear by my own name,' decrees the Lord, 'that because you have done this and have not withheld your son, your only son,

so that I may make you solemnly promise by the Lord, the God of heaven and the God of the earth: You must not acquire a wife for my son from the daughters of the Canaanites, among whom I am living.

And Judah spake unto him, saying, The man did solemnly protest unto us, saying, Ye shall not see my face, except your brother be with you.