'Certain' in the Bible

For before certain men came from James, he did take food with the Gentiles: but when they came, he went back and made himself separate, fearing those who were of the circumcision.

Be certain, then, that those who are of faith, the same are sons of Abraham.

Brothers, as men would say, even a man's agreement, when it has been made certain, may not be put on one side, or have additions made to it.

I am certain about you in the Lord, that you will be of no other mind; but he who is troubling you will have his punishment, whoever he is.