I've recently been reading Avraham Gileadi's interpretation of Isaiah. I agree with his interpretation of the Isaiah verses I've used (Isaiah 50:10-11). His interpretation is as follows:
For verse 10: He implies, because these two ideas are in parallel, that those who fear the Lord are the ones who heed the voice of the Servant. Those who don’t fear the Lord don’t heed his voice. The Servant is the light who is sent to light up the darkness of these people. So those are all word links. They’re also metaphors. The voice is the Servant himself, in that sense, and thelight is the Servant himself. He personifies the light. Walking in the darkness, since the king of Assyria, and Babylon personifies darkness, it means that you’re influenced by him, in a metaphorical sense, on that level. But, if you trust in the Lord, and rely upon God, it has its own power—then the light begins to dawn for you and things begin to make sense out of the chaos, out of the confusion. And then there is hope and there’s the possibility of deliverance for you, from the powers of darkness, from the king of Assyria, and from the destruction of Babylon, from the Sodom and Gomorrah calamity.
For verse 11: Since he’s talking mainly, here, to a reprobate group—the ones who were cut of—or the ones who have alienated themselves, the ones who have a bone to pick him—this is the final summary. “ But you are lighters of fires, all of you, who illuminate with mere sparks. Walk then, by the light of your fires and by the sparks you have kindled. This shall you have from my hand: you shall lie down in agony.” In other words, they’re just trouble-makers who are lighting fires all over the place, that people need to keep putting out. The light of truth that they have is like a mere spark, in comparison to the light that the Lord has sent in the personhood of his Servant, or to the greater light that the Lord himself is. The Servant, although he’s a light, which is a power of creation, is only a forerunner to the Lord himself who is the greater light. He’s like the sun, peeking up over the horizon, and the Servant leads into God’s presence. But they won’t even have anything to do with the Servant, so they’re going to end up in agony. “This shall you have from my hand,” that is from his left hand, the king of Assyria. They will experience all of the covenant curses that come upon the wicked, through the instrumentality of the Lord’s left hand, the king of Assyria.
Here is his website: http://www.isaiahexplained.com