'Fast' in the Bible

but Christ as a son, over his house; whose house are we, if we hold fast our boldness and the glorying of our hope firm unto the end.

for we are become partakers of Christ, if we hold fast the beginning of our confidence firm unto the end:

Having then a great high priest, who hath passed through the heavens, Jesus the Son of God, let us hold fast our confession.

let us hold fast the confession of our hope that it waver not; for he is faithful that promised: