In which sutta does a lay disciple of the Buddha tell a non-buddhist mendicant that he has experienced jhana? I remember reading a sutta some time ago in which a lay disciple of the Buddha held a conversation with a non-Buddhist ascetic. I don't remember the topic of their conversation, but at one point the lay buddhist talked about having experienced jhana. Does anyone know which sutta this is?

Thanks in advance for your answers!
your best first try is this essay

perhaps this

When Do the Jhānas Become Necessary?


  While there seem to be no suttas that impose an inflexible rule to the
  effect that a lay noble disciple must possess the jhānas, there are at
  least two texts that explicitly ascribe all four jhānas to certain
  householders. One, found in the Citta-saṃyutta (SN 41:9/IV 300-2),
  features Citta the householder, the foremost lay preacher, in a
  conversation with a naked ascetic named Kassapa. Kassapa was an old
  friend of Citta who had embraced the life of renunciation thirty years
  earlier, and this is apparently their first meeting since that time.
  Kassapa confesses to Citta that in all these years he has not achieved
  any "superhuman distinction in knowledge and vision befitting the
  noble ones" (uttarimanussadhammā alamariya-ñāṇadassanavisesa); all he
  does is go about naked, with a shaved head, using a feather brush to
  sweep his seat. He then asks Citta whether, as a lay disciple of the
  Buddha, he has reached any distinguished attainments. Citta says that
  he has, and then declares his ability to enter and dwell in the four
  jhānas (he uses the standard formula). To this he adds: "Further, if I
  were to die before the Blessed One, it would not be surprising if the
  Blessed One would declare of me: 'There is no fetter bound by which
  Citta the householder might come back to this world.'"[32] Through
  this bit of coded text, partly a stock formulation, Citta is informing
  his friend that he is a non-returner with access to the four jhānas.
  
  The other sutta is AN 7:50/IV 66-67 and concerns the lay woman
  Nandamātā. In the presence of the Venerable Sāriputta and other monks,
  Nandamātā has been disclosing the seven wonderful and marvellous
  qualities with which she is endowed. The sixth of these is possession
  of the four jhānas, again described by the stock formula. The seventh
  is as follows: "As to the five lower fetters taught by the the Blessed
  One, I do not see among them any as yet unabandoned in myself."[33]
  This too is a coded way of declaring her status as a non-returner.


https://www.budsas.org/ebud/ebdha267.htm