妙法蓮華經玄贊 2.231

2.231

善逝者，謂於長夜具一切種自利、利他二功德故。逝者往也。謂成菩提已，於生死長夜具一切種二利功德善事往矣。故名善逝。

“Sugata” means possessing all varieties of the two merits of self-benefit and benefiting others throughout the long night. “Gata” means gone. That is, having attained bodhi, he has well gone throughout the long night of saṃsāra, equipped with all varieties of the good deeds of the two benefits. Therefore he is named Sugata.