妙法蓮華經玄贊 8.25

8.25

贊曰：此合中途方退。若但讚佛乘，眾生不能以是得度，久受勤苦故遂便退失，佛道長遠倦時長故、久受勤苦怖行大故。

The Commentary says: This correlates turning back midway. If he had only praised the Buddha Vehicle, sentient beings would not have been able to be delivered thereby; because they would long endure toil and suffering, they would thereupon turn back and lose it. The Buddha Path is long and distant because the duration of weariness is long; they would long endure toil and suffering because they feared the greatness of the practice.