A handwritten letter written by Rosa Parks recalling Rev. Martin Luther King Jr.’s work in the civil rights movement is on sale for $54,000.

The letter, dated Oct. 6, 1981, was sent to a Mr. Kessler more than a decade after King’s assassination.

“I admired and respected him as a truly great man committed and dedicated to freedom, peace, and equality for all oppressed humanity,” Parks writes about King in the letter. “He was a leader of the masses in Montgomery, Alabama, and the nation.”

Moments in Time CEO Gary Zimet, whose company is selling the letter, told AL.com it’s the only letter where he’s seen Parks mentioning King, and said it’s rare because it’s handwritten. “Even her typed letters are scarce,” Zimet said.

Parks was arrested after refusing to give up her seat to a white passenger on a segregated bus in Montgomery on Dec. 1, 1955. Her arrest sparked the Montgomery bus boycott, a pivotal moment in the civil rights movement.

The boycott turned King, who was a young minister, into a leader in the movement. The 381-day protest of the segregated bus system ended with a U.S. Supreme Court ruling that segregated public buses were unconstitutional.

Parks died in 2005 at age 92. A statue commemorating her life now stands in Montgomery.