大毘盧遮那成佛經疏 2.84

2.84

第五十五「云何剃刀心？謂唯如是依止剃除法」者，剔除鬢髮是離俗出家相。謂此人心但作是念：「我已剔除俗相，令惡法不得復滋，更何所求？」當知此心最惡，以自作分限故，能剃所有善根令不得生。當念一切賢聖所應斷者，所謂無明住地三毒之根，若能剃此令妄想不生，乃名真出家也。

As for the fifty-fifth, “What is the razor-like mind? It refers to only relying on the method of shaving in this manner”: Shaving the hair and beard is the mark of renouncing the world and leaving home. This means that this person's mind merely conceives this thought: “I have already shaved off worldly marks so that bad dharmas cannot grow again; what more should I seek?” One should know that this mind is the worst: because it sets its own limits, it can shave away all roots of goodness, preventing them from growing. One should contemplate that what all the worthy and noble ones ought to sever is the so-called root of the three poisons in the stage of ignorance-traces. If one can shave this so that delusive thoughts do not arise, only then is it called truly leaving home.