佛說觀佛三昧海經 4.24

4.24

佛告阿難：「汝持佛語真實莫忘，為諸比丘當廣宣說。」說是語時，五百比丘得四大定，同時皆得四沙門果。

The Buddha said to Ānanda: "You must retain the Buddha's words in truth and not forget them, and you must widely proclaim them to the monks." When these words were spoken, five hundred monks attained the samādhis of the four great elements, and at that very moment all attained the four fruits of ascetic life.