Once Pasenadi, uncomfortable and short of breath after a heavy meal, visited the Buddha. The Buddha admonished him on the evils of gluttony and taught his nephew Sudassana, who came with Pasenadi, a verse to be repeated whenever food was placed before the king. The king paid the young man one hundred coins (kahāpaṇa) daily for this service. Pasenadi profited by the lesson and became healthy. S.i.81.
The Dhammapada Commentary at DhA.iii.264 f gives a fuller version of this story. There Sudassana is described as the king’s nephew. This is also probably the incident mentioned at DhA.iv.15 f; but the youth there is called Uttara.