I am searching for a story, I don't know exactly where, but I guess it might be in the commentary stories to the Dhammapada.
It is about a monk (at the Buddha's time, I suppose) who is a great teacher, who instructs many students up to the point that they are attaining the path and fruit to stream-entry or beyond to even arahatship. But he himself is still a putthujana, yet all the time crazy busy teaching all the time.
One day one of his students who has become an arahant asks himself: Well, what level of insight has my good teacher who helped me to this here, attained? And he sees (through mind-reading) that his teacher is still a putthujana. So he comes flying through the air to his teacher and teaches him a lesson. Something like "You don't even have time for yourself, still not having attained path and fruit."
The teacher is shocked and realizes the truth in this. So he goes off into the woods, into seclusion to meditate and strive for enlightenment. For days or weeks or however long, he grows more and more desperate, wanting to finally come to a breakthrough of insight and is totally stressed out. So at one point he simply breaks down crying.
Some devas come and imitate him crying. He asks them politely: "WTF!?" And they say: "Well, you're our great teacher. We just repeat what you do, trusting that it will lead us closer to spiritual realization."
He is embarrassed and shaken up by this and finally has some very strong yet calm determination to reach the goal of his practice. And very soon he finally becomes an arahat.
Can someone point me to the source of this story in the canon?
Thanks in advance.