The story discusses the dedication of Aaruni exhibited towards his teacher and the relationship that Sanatana Dharma expects between a Teacher and Disciple.
SRIMAD MAHABHARATA – AADI PARVA – PAUSHYA (UPA) PARVA – PART 3 (B) – THE STORY OF AARUNI
“About this time there was a Rishi, Ayoda-Dhaumya by name. Ayoda-Dhaumya had three disciples – Upamanyu, Aaruni, and Veda. The Rishi (Ayoda-Dhaumya) ordered one of these disciples – Aaruni of Paanchaala, to go and stop up a breach in the water-course of a certain field. Aaruni of Paanchaala, thus ordered by his Upaadhyaaya, went to the spot. Having gone there he saw that he could not stop up the breach in the water-course by ordinary means. He was upset because he could not do his Upaadhyaaya’s command. But after a long time, he (Aaruni) saw a way and said, ‘Well, I will do it in this way.’ He (Aaruni) then went down into the breach and lay down himself there. The water was thus confined.
“Some time after, the Upaadhyaaya Ayoda-Dhaumya asked his other disciples where Aaruni of Paanchaala was. They answered, ‘Sir, he has been sent by yourself saying – ‘Go, stop up the breach in the water-course of the field.’ Thus reminded, Dhaumya, addressing his pupils, said, ‘Then let us all go to the place where he is.’
“Having arrived there, he shouted, ‘Ho Aaruni of Paanchaala! Where are you? Come here, my child.’ Aaruni hearing the voice of his Upaadhyaaya speedily came out of the water-course and stood before his Guru. Addressing the latter (Ayoda-Dhaumya), Aaruni said, ‘Here I am in the breach of the water-course. Not having been able to identify any other means, I entered myself (into the breach) for the purpose of preventing the water running out. It is only upon hearing your voice that, having left it and allowed the waters to escape, I have stood before you. I salute you, Master; tell me what I have to do.’
“The Upaadhyaaya (Ayoda-Dhaumya), thus addressed, replied, ‘Because in getting up from the ditch you have opened the water-course, from now on you shall be called Uddaalaka as a mark of your Upaadhyaaya’s favour. Because my words have been obeyed by you, you (Aaruni of Paanchaala) shall obtain good fortune. All Vedas shall shine in you and all the Dharmasastras also.’ Aaruni, thus addressed by his Upaadhyaaya (Rishi Ayoda-Dhaumya), went to the country after his heart (possibly Paanchaala).