In late July 2006, Mr. Castro, who is 81, handed over power temporarily to his brother, Raúl Castro, 76. …

Now, just days before the national assembly is to meet to select a new head of state, Mr. Castro resigned permanently in a letter to the nation. …

“I will not aspire to neither will I accept — I repeat I will not aspire to neither will I accept — the position of President of the Council of State and Commander in chief,” he wrote.

He added: “It would betray my conscience to occupy a responsibility that requires mobility and the total commitment that I am not in the physical condition to offer.”

James C. McKinley, Jr., "Fidel Castro Resigns as Cuba’s President," New York Times