'Faithful' in the Bible

And I will raise up for myself a faithful priest, who shall do according to what is in my heart and in my mind; and I will build him a sure house; and he shall walk before mine anointed continually.

And Ahimelech answered the king and said, And who is so faithful among all thy servants as David, who is the king's son-in-law, and has access to thy secret council, and is honourable in thy house?