'Faithful' in the Bible

And the faithful of the circumcision were astonished, as many as came with Peter, that upon the nations also the gift of the Holy Spirit was poured out:

But that he raised him from among the dead, no more to return to corruption, he spoke thus: I will give to you the faithful mercies of David.

And when she had been baptised and her house, she besought us, saying, If ye have judged me to be faithful to the Lord, come into my house and abide there. And she constrained us.