The Prophet said: "He who slaps (his) cheeks, tears (his) clothes and calls with the call of the Jahliyyah is not one of us."
Jami` at-Tirmidhi Book 10, Hadith 35
← Previous Hadith "When the news of the death of Ja'far came, the Prophet said: 'Prepare some food for the family of Ja'far, for indeed something has happened to them that will keep them busy.'"

Jami` at-Tirmidhi Book 10, Hadith 34 Next Hadith → "A man died among the Ansar named Qarazah bin Ka'b, and he was being wailed over. So Al-Mughirah bin Shu'bah came and ascended the Minbar. He uttered thanks and praise to Allah and said: "As for the gravity of wailing in Islam, indeed I heard the Messenger of Allah saying: 'The one who is wailed over is punished as long as he is being wailed over.'"

Jami` at-Tirmidhi Book 10, Hadith 36