From this videoconference talk from 22 February 2019, Ajahn Anan discusses Magha Puja and Venerable Cula Panthaka.

An excerpt: "“My Lord Buddha, my brother drives me away, so I am going to disrobe.” The Buddha then said to bring up awareness in Cula Panthaka, “Cula Panthaka, when did you ordain for your older brother? Didn’t you ordain for yourself? When your older brother told you to leave, why didn't you come to me? Come. Stay with me.”"

Note: One can read Dhamma talk transcripts at the Wat Marp Jan 'Reflections' page. These include questions and answers with Ajahn Anan, which are not in the audio files. See this talk's transcript here: https://watmarpjan.org/en/magha-puja-and-culapanthaka/