How does Martin Luther King, Jr. establish credibility (ethos) in the "I Have a Dream" speech?

Opening his speech Martin Luther King Jr. sets up his credibility with his use of ethos, referring to the Declaration of Independence saying, “This note was a promise that all men… would be guaranteed the unalienable rights of life.”

Explanation:

a, both were musicians during the jazz age

the supreme court can hear any case it wishes as long as four justices agree to hear it.

hope this , give me brainliest answer =j