Ikrimah narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) concerning the story of a man who killed his wife because she reviled the Prophet (peace and blessings be upon him). He said: "Last night she mentioned you and reviled you. I could not bear it, so I took a mighwal (a small dagger) and plunged it into her belly." The Prophet (peace and blessings be upon him) said: "Bear witness that her blood is unavenged (no retribution is due for it)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20434