I looked it up and found this from an article

West said Martin Luther King, Jr. told the youth in Birmingham to put on their “good clothes” because those good clothes were cemetery clothes, and they had to be “coffin ready,” given their commitment to love and justice.

He went on to say, “So, every morning I put on my cemetery clothes. I’m coffin ready” The scarf, he said, has to do with his preserving his voice. Something he learned from Luther Vandross.