Isaiah 50

Vs. 4
        After the Eternal God finishes rebuking Isaiah and his people as chapter fifty begins, Isaiah responds with a summation of his ministry.
        The way many translations render vs. 4, Isaiah appears to tout his qualifications to teach, but reading the ESV suggested another possible meaning. That version says, "The Lord GOD has given me the tongue of those who are taught, that I may know how to sustain with a word him who is weary." It carries the idea of the teacher adapting his presentation style to the peculiarities of his students, speaking so they can readily understand.
        The second thought in vs. 4 describes the process in more detail: "Morning by morning he awakens; he awakens my ear to hear as those who are taught." The phrase "Morning by morning" suggests the process includes the prophet's daily time of confession, praise, supplication and meditation.

Vs. 5
        The Lord GOD has opened my ear, and I was not rebellious; I turned not backward.
(Isaiah 50:5 ESV)

        Isaiah carefully credits 'ădônây yehôvâh, the Eternal, Self-Existent Lord with enabling the teacher to discern his students' needs.

Vs. 6
        I gave my back to those who strike, and my cheeks to those who pull out the beard; I hid not my face from disgrace and spitting.
(Isaiah 50:6 ESV)

        Does this verse sound as appealing as the previous two? The other side of the teacher's figurative coin is the abuse any prophet/teacher can expect by preaching and teaching God's word without respect to his audience's preferences.
        Trouble is, in today's economy the preacher/teacher must remain, to a degree, in his audience's favor to remain employed. On the rare occasion, however, when he is invited to guest-preach, he can speak his mind without political constraint.

Vs. 7
        But the Lord GOD helps me; therefore I have not been disgraced; therefore I have set my face like a flint, and I know that I shall not be put to shame. 
(Isaiah 50:7 ESV)

        Is this a promise today's preacher/teacher can take to the bank, perhaps, in lieu of a pay check? It certainly stands as a challenge to present God's truth without respect to the audience's sensibilities.
        That said, we must balance this truth with vs. 4 of this chapter. While those in authority must not worry about offending sinners with God's truth, they must present it in a way they will understand, without allowing personal prejudices to alienate them. If sinners in the audience are to be offended, it must be God's word, and not the preacher's personality that does the offending.

Vs. 8
        "He who vindicates me is near. Who will contend with me? Let us stand up together. Who is my adversary? Let him come near to me."
(Isaiah 50:8 ESV)

        Here is the prevailing attitude any prophet/teacher must seek. He must not attempt to vindicate(make excuses) for himself. If we proclaim God's truth, it is His job to vindicate us. And let people try to argue against God's truth; when God speaks through someone, He stands with the speaker.
        This is where God's prophet/teacher must not allow God's truth to languish under his own pride. Where one stands confident in his own personal grasp of the truth, he endangers God's eternal truth with his own mediocrity and the stain of his own pride.

Vs. 9
        "Behold, the Lord GOD helps me; who will declare me guilty? Behold, all of them will wear out like a garment; the moth will eat them up."
(Isaiah 50:9 ESV)

        Isn't the confidence displayed by one bearing God's commission a beautiful thing? Cleopas and his friend observed that very thing when, on the Emmaus Road, Jesus joined their party and spoke with them: They said to each other, "Did not our hearts burn within us while he talked to us on the road, while he opened to us the Scriptures?"
(Luke 24:32 ESV)
        Our reaction to that account goes like this, "I can't hope to speak with the same power and authority as the resurrected Jesus."
        God's response? Luke 21:10-15 ESV  Then he said to them, "Nation will rise against nation, and kingdom against kingdom. (11) There will be great earthquakes, and in various places famines and pestilences. And there will be terrors and great signs from heaven. (12) But before all this they will lay their hands on you and persecute you, delivering you up to the synagogues and prisons, and you will be brought before kings and governors for my name's sake. (13) This will be your opportunity to bear witness. (14) Settle it therefore in your minds not to meditate beforehand how to answer, (15) for I will give you a mouth and wisdom, which none of your adversaries will be able to withstand or contradict.
        Vs. 14 of Luke 21 shouldn't be taken as license to avoid studying God's word, but just the opposite. Readying ourselves to give an answer to our inquisitors by rehearsing prepared scripts is always counterproductive. Such an approach gives us no flexibility in responding to challenges. Only an in depth understanding of God's word will do that, and only time spent in His word will provide that understanding.
        That said, those of us with a less than adequate understanding of God's word can't allow our ignorance to intimidate us. If the Spirit of Jesus has filled our blood-cleansed soul, He has changed us. God commanded us to share those changes with others, even if we don't know the book-chapter-verse of Biblical proof-passages.

The last two verses of chapter 50 fire a parting shot at not only God's prophets and teachers, but at their constituency as well, and pretty much speak for themselves.
        Isaiah 50:10-11 ESV Who among you fears the LORD and obeys the voice of his servant? Let him who walks in darkness and has no light trust in the name of the LORD and rely on his God. (11) Behold, all you who kindle a fire, who equip yourselves with burning torches! Walk by the light of your fire, and by the torches that you have kindled! This you have from my hand: you shall lie down in torment.