觀無量壽佛經義疏 3.109

3.109

「『此菩薩坐時，七寶國土一時動搖。』」即本國也。二、分身說法。

"‘When this bodhisattva sits, the seven-jeweled land trembles all at once.’" That is to say, his own land. Second, the emanation bodies preaching the Dharma.