妙法蓮華經文句 2.57

2.57

觀門者，觀六根清淨具千功德，雖眼有八百，耳千二百，以多足少，數滿六千，表本法門，亦是觀行意也。

As for the approach of contemplation: contemplating that the purity of the six sense faculties possesses a thousand virtues—although the eyes have eight hundred and the ears twelve hundred, by supplementing the lesser with the greater, the number is filled to six thousand, expressing the original Dharma gate, which is also the meaning of the practice of contemplation.