法華三昧懺儀 1.18

1.18

初入道場，當以香湯沐浴、著淨潔衣，若大衣及諸新染衣；若無當取己衣勝者，以為入道場衣。於後若出道場，至不淨處，當脫去淨衣著故衣；所為事竟，當更洗浴著本淨衣，入道場行事也。

When first entering the bodhimaṇḍa, one should bathe with fragrant water and wear clean clothes, such as the saṅghāṭī robe or other newly dyed clothes; if these are lacking, one should take the best of one's own clothes to serve as the garments for entering the bodhimaṇḍa. Later, if one leaves the bodhimaṇḍa to go to an impure place, one should take off the clean clothes and put on old clothes; when the business is finished, one should bathe again, put on the original clean clothes, and enter the bodhimaṇḍa to conduct the practice.