大方廣佛華嚴經隨疏演義鈔 89.26

89.26

疏二十四「佉字」，若會經者，智慧等空，故能含藏。《智論》云「若聞呿字，知一切法等於虛空不可得義，以呿伽此言虛空故。」

In the commentary on the twenty-fourth [syllable], 'kha' (佉), if correlated with the sūtra, wisdom is equal to space, and thus is able to contain and store. The Mahāprajñāpāramitopadeśa states: 'If one hears the syllable kha (呿), one knows the ungraspable meaning that all phenomena are equal to empty space, because khaga (呿伽) here means empty space.'