大般涅槃經疏 28.30

28.30

「我於處處」下，第二十一有十方佛無十方佛。薩婆多明無，僧祇明有，《成實》一世界則無、多世界則有。

From "In various places, I" below, the twenty-first is whether there are buddhas of the ten directions or no buddhas of the ten directions. The Sarvāstivādins explain that there are none; the Mahāsāṃghikas explain that there are; the *Tattvasiddhi-śāstra* holds that in a single world there are none, but across multiple worlds there are.