'Faithful' in the Bible

I will raise me up a faithful priest, that shall do according to that which is in my heart and in my mind. I will build him a sure house; and he shall walk before my anointed forever.

Then Ahimelech answered the king, and said, "Who among all your servants is so faithful as David, who is the king's son-in-law, and is taken into your council, and is honorable in your house?