大日經持誦次第儀軌 1.124

1.124

A, seat, aṃ: the earth-realm of great compassion; because it is upheld by the vajra jewel ground beneath the vajra seat. Just as the earth can produce the myriad things and bear all the world without being shaken; in this way, the ground of omniscience is born from the Tathāgata's vajra nature, and that which is thus born is ultimately unborn, able to give birth to the myriad virtues of bodhi, and to uphold the mind-ground of all the worthy and noble ones without being destroyed.