'Behalf' in the Bible

I heard the voice of the sovereign master say, "Whom will I send? Who will go on our behalf?" I answered, "Here I am, send me!"

Perhaps the Lord your God will hear all these things the chief adviser has spoken on behalf of his master, the king of Assyria, who sent him to taunt the living God. When the Lord your God hears, perhaps he will punish him for the things he has said. So pray for this remnant that remains.'"

So I will assign him a portion with the multitudes, he will divide the spoils of victory with the powerful, because he willingly submitted to death and was numbered with the rebels, when he lifted up the sin of many and intervened on behalf of the rebels."