大方廣圓覺修多羅了義經略疏 2.673

2.673

多生業累恐障淨心，懺悔求哀，發露先罪。日數若少，慮不精誠，三七日中已彰懇禱。懺悔之義，下道場加行中當釋。

Fearing that karmic burdens from many lifetimes might obstruct the pure mind, one repents and beseeches with sorrow, disclosing past transgressions. If the number of days were fewer, one might not be sincere and devoted; within three times seven days, earnest prayers have already been manifested. The meaning of repentance will be explained below under the preliminary practices of the bodhimaṇḍa.