'Pair' in the Bible

Thus saith the LORD; For three transgressions of Israel, and for four, I will not turn away the punishment thereof; because they sold the righteous for silver, and the poor for a pair of shoes;

That we may buy the poor for silver, and the needy for a pair of shoes; yea, and sell the refuse of the wheat?

And to offer a sacrifice according to that which is said in the law of the Lord, A pair of turtledoves, or two young pigeons.

And when he had opened the third seal, I heard the third beast say, Come and see. And I beheld, and lo a black horse; and he that sat on him had a pair of balances in his hand.