大方廣佛華嚴經入法界品四十二字觀門 1.7

1.7

曩（舌頭呼）字時，入無阿賴耶際般若波羅蜜門，悟一切法性相不可得故。

When pronouncing the letter NA (pronounced with the tongue-tip), one enters the perfection of wisdom door of the limitless Ālaya, because one realizes that the nature and characteristics (nāma) of all dharmas cannot be apprehended.