三彌勒經疏 1.85

1.85

經曰「時宮四角」以下，第四作柱。四寶柱者，表四十九重法堂之四柱也。梵摩尼者，淨摩尼，或云梵王如意珠也。

Where the sūtra states, "At that time, at the four corners of the palace," onward: fourth, this concerns making the pillars. The "four jeweled pillars" signify the four pillars of the forty-nine tiers of the Dharma hall. "Brahmamaṇi" refers to a pure maṇi, or is said to be the cintāmaṇi of Brahmā.