法華論疏 3.145

3.145

釋第二中云多寶如來入於涅槃，此句標世間涅槃平等章門也。世間涅槃彼此平等無差別故者，以多寶如來常在十方世界中，而稱入涅槃，故知世間涅槃平等。

In explaining the second, the statement that Prabhūtaratna Tathāgata entered nirvāṇa introduces the section heading of the equality of the worldly and nirvāṇa. "The worldly and nirvāṇa, one and the other, are equal and without distinction" means that Prabhūtaratna Tathāgata is constantly in the worlds of the ten directions, yet is said to have entered nirvāṇa; therefore, we know that the worldly and nirvāṇa are equal.