We read in the Sutta Nipata (Chapter III, the Great Chapter, 10, Kokāliya,
''Khuddaka Nikāya'') that while the Buddha was staying at Savatthī, the
bhikkhu Kokāliya visited him. Kokāliya spoke evil of Sāriputta and Moggallāna,
saying that they had evil desires. Three times the Buddha told him not to
speak in that way. After Kokaliya had departed boils developed all over his
body which became bigger and bigger and discharged pus and blood. He died
and was reborn in the Paduma hell. Later on the Buddha told the monks
about Kokāliya's evil speech and his rebirth in hell. We read (vs. 657, 658)
that the Buddha said:
Surely in the mouth of a man,
when born, an axe is born,
with which the fool cuts himself,
saying a badly-spoken (utterance).
He who praises him who is to be blamed,
or blames him who is to be praised,
accumulates evil by his mouth.
Because of that evil he does not find happiness...