What was the relationship between Azariah and Mishael?
In the furnace, Azariah stood up and prayed. Then the three young men sang together with one voice. Daniel 3:25, 51
What the Bible says
Daniel 3:51
Then these three as with one mouth praised, and glorified, and blessed God in the furnace, saying:
Daniel 3:52
Blessed art thou, O Lord the God of our fathers: and worthy to be praised, and glorified, and exalted above all for ever: and blessed is the holy name of thy glory: and worthy to be praised, and exalted above all in all ages.
Douay-Rheims Bible (Challoner revision), public domain.