梵網經菩薩戒本疏 6.108

6.108

六、輕重者，由不發願，廢所修行，有多有少，故有輕有重。又忘本誓，有多時少時，故有重輕可知。

Sixth, regarding severity: due to not making vows, what practice is neglected may be more or less, hence there are light and heavy degrees; also, forgetting the original vows may be for a long time or a short time, hence there are heavy and light degrees, which may be understood.