"I have heard that on one occasion the Blessed One was staying near Sāvatthī at Jeta’s Grove, Anāthapiṇḍika’s monastery. And on that occasion a certain monk was sitting not far from the Blessed One, his legs crossed, his body held erect, enduring fierce pains, sharp & severe, that were the result of old kamma—mindful, alert, without suffering. The Blessed One saw him sitting not far away, his legs crossed, his body held erect, enduring fierce pains, sharp & severe, that were the result of old kamma—mindful, alert, and not struck down by them.

Then, on realizing the significance of that, the Blessed One on that occasion exclaimed:

For the monk who has left
all kamma behind,
shaking off the dust of the past,
steady, unpossessive,
Such:
There’s no point in telling
anyone else."

Kamma Sutta