'Master' in the Bible

I will hand the Egyptians over to the power of a cruel master, and a fierce king will rule over them," declares the Lord GOD of the Heavenly Armies.

Come now, all of you, make a bet with my master, the king of Assyria: I will give you two thousand horses, if you can furnish riders for them!

But the field commander asked, "Was it only to all of you and to your master that my master sent me to speak these things? Wasn't it also to the men sitting on the wall who, like you, will have to eat their own excrement and drink their own urine?"

Perhaps the LORD your God will hear the words of the field commander, whom his master, the king of Assyria, sent to mock the living God, and perhaps he will rebuke the words that the LORD your God has heard. So lift up a prayer for the remnant that still survives in this city."

"Here is what to tell your master," Isaiah told them. "This is what the LORD says: "Don't be afraid of the words you've heard those words with which the underlings of the king of Assyria have insulted me.