《汉书·纪·平帝纪》
天下官吏俸同二千石以上年老退休的，三分其原禄，用三分之一与其本人，以养天年。
天下吏比二千石以上年老致仕者，参分故禄，以一与之，终其身。
Officials throughout the Empire who retire due to old age with a salary of 2,000 shi or more shall have their original emoluments divided into three parts, one part of which shall be given to them to sustain their old age.