Teaching the Dhamma (Dhammadesana), having heard the good, is one of the higher meritorious deeds, practiced by instructed, not regarded as useless question & answer ways, as from outsider often thought, but after hearing the Dhamma, one of the five ways to gain release, awakening.
...“Further, it’s not that the Teacher or a fellow person leading the holy life teaches the Dhamma to the monk. But the monk teaches the Dhamma to others in detail, as he has heard it, as he has learned it. And in whatever way he teaches the Dhamma to others in detail, as he has heard it, as he has learned it, in just that way the monk, with regard to that Dhamma, is sensitive to the meaning, is sensitive to the Dhamma. In him—sensitive to the meaning, sensitive to the Dhamma—joy is born. When he is joyful, rapture is born. In one who is enraptured at heart, the body grows calm. When the body is calm, one feels pleasure. Feeling pleasure, the mind becomes concentrated. This, monks, is the second opening to release… Vimutti Sutta
Maybe one or another likes to teach about such occasions, as he had heard, shares stories of how it came to release.
What are retelling of occasions where the one who taught gained paths and fruits?
[Note that this isn't given for stacks, excange, other world-binding trades but for release from this wheel]