Excessive Joking

The Prophet (sal Allahu alaihi wa sallam) said to his Companions (radi Allahu anhum): “Who will take these words and apply them, or knows someone who will?” Abu Hurairah (radi Allahu anhu) answered, “I will, O Messenger of Allah,” whereupon the Prophet (sal Allahu alaihi wa sallam) took his hand and enumerated five things, saying:

“Avoid the unlawful (deeds) and you will be the most religious of people.”
“Be satisfied with what Allah has alotted you and you will be the richest of people.”
“Treat your neighbour well and you will be a believer.”
“Love for others what you love for yourself and you will be a Muslim.”
“Avoid excessive laughter for too much laughter kills the heart.” [Ahmad]

Imam Nahlawi says: “The necessary condition for the permissibility of joking is that it does not contain lies or occasion fright, because this hurts others, and we are forbidden to do so.”

“Excessive joking is blameworthy since it eliminates one’s dignity and reserve, and creates resentment in certain situations and people. It also causes immoderate laughter, which kills the heart.” [al-Durar al-Mubaha fi al-Hazr al-Ibaha, quoted in "Reliance of the Traveller" by Ahmad ibn Naqib al-Misri]