宋高僧傳 23.19

23.19

系曰：煉大拇指，火盡灰飛，如何於焦炭之末，骨肉隨生不久如故？此與火中蓮華，同種而異態耳。何謂三白？通曰：「事理二種：一白飯、白水、白鹽，事也；二身不遍觸，口誦真經，意不妄緣。此三明白，非黑業也。故享此名歟。」

The appraisal says: He burned his thumb, and when the fire went out, the ashes flew away; how could bone and flesh then regrow shortly afterward from the powder of charred cinders, just as before? This and the lotus in the fire are of the same kind, yet different in manifestation. What is meant by the 'three whites'? In general, it is said: 'There are two kinds, the phenomenal and the noumenal. First, white rice, white water, and white salt are the phenomenal. Second, the body does not touch anything improperly, the mouth recites the true sūtras, and the mind does not stray to false conditions. These three are luminous and white, not black karma. Hence he was called by this name.'