It seems odd to encourage those who preach Holy Tuesday to preach Jesus, but that seems to be where the Book of Concord goes with these texts.

Isaiah 49:1-7

[The LORD] says,
“It is too light a thing that you should be my servant
    to raise up the tribes of Jacob
    and to restore the survivors of Israel;
I will give you as a light to the nations,
    that my salvation may reach to the end of the earth.”
-- Isaiah 49:6

Verse 6 is quoted in Formula of Concord, Solid Declaration, Article 5: Law and Gospel (SD 5:23) near the end of a paragraph noting the continual proclamation of law and gospel, especially in the hope for the one "through whose wounds we have been healed" (SD 5:23).

1 Corinthians 1:18-31

For since, in the wisdom of God, the world did not know God through wisdom, God decided, through the foolishness of our proclamation, to save those who believe.
-- 1 Corinthians 1:21

Verse 21 is cited twice in Formula of Concord, Solid Declaration, Article 2: Free Will. The first citation (SD 2.10) is a quote, along with several others, noting that without the Spirit's gift of faith, neither reason or intelligence can make sense of the gospel. The second citation (SD 2.51) is also a quote of the verse, again with several others, to show that God wants all people to hear the gospel.

Verses 21, 30, and 31 are cited in Formula of Concord, Solid Declaration, Article 11: Election (SD 11.12) to show that in the matter of God's foreknowledge of who will be saved, scripture points us to the Word, who is Jesus, for both comfort and censure.

He is the source of your life in Christ Jesus, who became for us wisdom from God, and righteousness and sanctification and redemption, in order that, as it is written, “Let the one who boasts, boast in the Lord.”
-- 1 Corinthians 1:30-31

Verse 30 is quoted in Apology of the Augsburg Confession, Article 4: Justification (AP 4.86) to show what faith receives, namely the promise of God in Jesus, who is our righteousness.

Verse 30 also comes up in Formula of Concord, Epitome, Article 3: Righteousness (Ep 3.1) as a passing reference for Jesus' two natures.

Verse 30 is cited a third time, again in Formula of Concord, but not where you might expect. Instead of Solid Declaration, Article 3, it comes up in Solid Declaration, Article 5: Law and Gospel (SD 5.22). The verse is quoted here as encouragement to trust in God alone.

Verse 31 is quoted in Smalcald Articles, Part 3, Article 13: How a Person is Justified and Concerning Good Works (SC 3.13.3) to finally show that good works do not lead to faith or salvation, but that they come from faith, which is a gift. Therefore, we cannot boast in our works, or in faith.

TheoThru

Should you be preaching this day, please remember this emphasis on faith as God's gift.

What do we trust that is not God?
How do we strive for righteousness that does not save?