大毘盧遮那成佛經疏 10.74

10.74

吽此心是種子也。訶字是行同於大空，下有鄔字是三昧，上點即大空行三昧也。憑此進修得至寶所故，能自在與人令滿所願也。

*Hūṃ*: this heart is the bīja. The syllable *ha* is practice identical to great emptiness; having the syllable *u* below is samādhi; the dot on top is the great emptiness practice samādhi. Relying on this to advance in cultivation, one is able to reach the treasure place; hence one can freely give to others, causing their wishes to be fulfilled.