Prison Serenity

In the prison of Puzzlania are many criminals, hardened and otherwise. One of them, a man called Frank, had during his stay come to regret and renounce his previous life of crime, due to finding religion - Zen Buddhism, specifically.
This was a matter of no importance whatsoever to most of the other inmates, but one other prisoner, by the name of Bubba, for some reason took a strong dislike to Frank because of this, and mercilessly taunted him for it (the security in the prison of Puzzlania is good enough that he did not get any opportunities to show his dislike in a more physical manner).
Frank, of course, was not particularly pleased about this, but he kept his serenity and ignored Bubba.

On the day Bubba was to be released, however, as he was passing by Frank's cell on his way to freedom, he called out an insult so incredibly vile (suffice it to say that it involved Frank's mother, a Buddha statue and a deceased yak) that he could not help but scream in rage and reach for Bubba, but the bars of his cell stopped him, of course. Bubba left the prison laughing.

A few weeks later, one of Frank's friends was about to be released, and he came to him to say goodbye.
"Got any words of wisdom before I leave?" he asked.
Frank took a deep breath and...

What did he say?