'Certain' in the Bible

In the hope of eternal life, which was made certain before eternal time, by the word of God who is ever true;

A certain one of them, a prophet of their own, said -- 'Cretans! always liars, evil beasts, lazy bellies!'

This is a true saying; and it is my desire that you may give certain witness about these things, so that those who have had faith in God may give attention to good works. These things are good and of profit to men;