Verses with the word steadfast in the Apocrypha (2 verses):

Wisdom of Solomon 7:23
Kind to man, steadfast, sure, free from care, having all power, overseeing all things, and going through all understanding, pure, and most subtil, spirits.

Additions to Esther 13:3
Now when I asked my counsellors how this might be brought to pass, Aman, that excelled in wisdom among us, and was approved for his constant good will and steadfast fidelity, and had the honour of the second place in the kingdom,