大方廣佛華嚴經入法界品四十二字觀門 1.6

1.6

左（輕呼）字時，入普輪斷差別般若波羅蜜門，悟一切法無諸行故。

When pronouncing the letter CA (pronounced lightly), one enters the perfection of wisdom door of the universal wheel cutting off differentiations, because one realizes that all dharmas are devoid of conditioned formations (cyavana/caryā).