大方便佛報恩經 1.20

1.20

Then that buddha said to the bodhisattvas: "Good sons! When you go to the Sahā world and see that buddha, you should give rise to thoughts of making offerings, showing reverence, and [recognizing how] difficult it is to encounter [him]. Why is this? Śākyamuni Tathāgata, throughout immeasurable hundreds of thousands of ten-millions of kotis of asaṃkhyeya kalpas, underwent difficult practices and austerities, and made a great compassionate vow: 'When I attain Buddhahood, it should be in a defiled and evil land, with mountains and mounds, rubble and thorns, wherein sentient beings are fully beset by afflictions and the five deadly sins and ten unwholesome deeds; amidst them I shall attain Buddhahood to benefit them, causing them to sever all suffering, obtain all bliss, accomplish the dharmakāya, and end [samsara] forever without remainder.' Such was that buddha's original vow. Now as you go, you should go as a buddha goes, and dwell as a buddha dwells."