Reference: Ghaaratul-Ashritah ‘alaa Ahlil-Jahli was-Safsatah – Volume 2, Page 109
Question: What is the extent of the authenticity of the hadeeth:
«Laughter [spiritually] kills the heart and removes the [spiritual] light from the face»
…and is it correct that it has been authenticated the Prophet (sal-Allaahu ‘alayhi wa sallam) laughed until his molars (teeth) were visible?
Response: The authentic hadeeth is:
«Beware of too much laughter, for indeed it [spiritually] kills the heart»
…and it is an authentic hadeeth and all praise is due to Allaah [alone] as I have made mention of it in “as-Saheeh al-Musnad mimmaa Laysa fis-Saheehayn”. And it has been authentically reported that the Prophet (sal-Allaahu ‘alayhi wa sallam) laughed until his molars were visible, however, this was not something regular, rather it was rare. Generally, the Prophet (sal-Allaahu ‘alayhi wa sallam) would [only] smile.