大方廣圓覺修多羅了義經略疏 2.1177

2.1177

若無勝利，須建道場，克志加功以期聖果，則三期皆是自利，為簡利他，故名無他事。亦可王賊、命難名為他事。定三期者，過則情生疲厭，少則功行未圓，故量克三期，亦無別義。然約三根配之，有其二意：一約障盡難易，配長期下根、中期中根、下期上根；二約精進懈怠配者，即反於此。根有利鈍，期有遠近，對病設藥，斯之謂歟。

If there is no superior benefit, one must establish a bodhimanda, setting one's will to exert effort in anticipation of the holy fruit; thus the three periods are all for self-benefit. To distinguish this from benefiting others, it is called "no other affairs." Alternatively, kings, bandits, and mortal danger may be called "other affairs." As for fixing three periods: if exceeding them, exhaustion and aversion will arise in one's feelings; if fewer, the practice of effort will not be complete. Hence one determines three periods by measure, with no further meaning. However, matching them to the three faculties has two senses: first, in terms of the difficulty or ease of exhausting obstacles, the extended period matches lower faculties, the intermediate period intermediate faculties, and the shorter period superior faculties; second, matching them in terms of diligence and laxity would be the reverse of this. Faculties have sharp and dull, periods have long and short; setting medicine according to the disease—is this not what is meant?