'Solemnly' in the Bible

Judah spoke to him, saying, "The man solemnly warned us, saying, 'You shall not see my face, unless your brother is with you.'

Now therefore listen to their voice: however you shall protest solemnly to them, and shall show them the way of the king who shall reign over them."

I solemnly command you by the Lord that this letter be read to all the holy brothers.