首楞嚴義疏注經 7.39

7.39

戒根為本，入道先門，師與證人一等清淨。師若有闕，資無所承，道場不就，職由斯矣。

The root of precepts is fundamental, the foremost gate for entering the Path; the preceptor and the witnesses must be equally pure. If the preceptor has a defect, the disciple has nothing to receive; that the bodhimanda is not accomplished is due to this.