Overall Meaning: Meaning of humour:
Muzah linguistically: Mazh is joking, and it is the opposite of seriousness (jidd). Mazaha yamzahu mazhan wa mizahan wa muzahan wa muzahatan (He jests, is jesting, a jest). [566] Lisan al-`Arab, Ibn Manzur (2/593); Taj al-`Arus, al-Zabidi (7/117).
Muzah technically: It is a form of simple, joyful talk with others in a kind and affectionate way without harming them. [567] Taj al-`Arus, al-Zabidi (7/117).

Difference between humour, buffoonery (hazl), and dissipation (mujun): [568] al-Furuq al-Lughawiyyah, al-`Askari (p. 254); al-Taysir bi-Sharh al-Jami` al-Saghir, al-Manawi (1/367).
Buffoonery necessitates the buffoon humiliating himself before those he is jesting, while humour does not necessitate that. Dissipation is having a stern face and no bashfulness.

Narrations reported in humour:
❖ Ibn `Umar, Allah be pleased with them both, said, “Allah’s Messenger ﷺ said, “Surely, I joke, and I do not say but truth.” [569] Reported by al-Tabarani in al-Mu`jam al-Saghir (779). al-Haythami agraded its chain as sound in Majma` al-Zawa’id (8/92). al-Albani authenticated it in Sahih al-Jami` (2494).
❖ Anas ibn Malik, Allah be pleased with him, said, “The Prophet ﷺ would not mix with us except that he would ask a younger brother of mine, ‘Abu `Umar, what did the little birdy do?’ [570] Reported by al-Bukhari (6129) and Muslim (2510). In this is proof of the permissibility of humour and repeated jesting. [571] Fath al-Bari, Ibn Hajar (10/584).

Quotes of the Predecessors and scholars on humour: [572] al-Lata’if wa al-Zara’if, al-Tha`labi (p. 151).
❖ Al-`Abbas, Allah be pleased with him, said, “The Messenger of Allah ﷺ was humorous, so humour became a Sunnah.”
❖ It was said to Sufyan ibn `Uyaynah, “Humour is a vice?” He replied, “No, it is a Sunnah. The issue is who does it well and places it where it ought to be placed.”
❖ Al-Murtada al-Zabidi said, “Being excessive in it and overstepping its limit compromises one’s decency and poise, but leaving it off completely and holding back from it compromises the Sunnah and the prophetic biography which we are commanded to follow and emulate. The best of matters are its moderate middle.” [573] Taj al-`Arus, al-Zabidi (7/117).

Categories of humour: [574] Mirqat al-Mafatih Sharh Mishkat al-Masabih, al-Qari (7/3061).
Humour is categorised into two:
Praiseworthy humour: It is that which is done rarely to lighten a conversation with a companion and be sociable with them, and this is a recommended Sunnah.
Blameworthy humour: It is that which is done excessively and is constantly practiced. It begets excessive laughter and a harsh heart, distracting from the remembrance of Allah and contemplating the missions of the religion. It will also often lead to harm, causing malice, doing away with one’s poise and gravitas.

Conditions of praiseworthy humour:
1- That it does not involve the mockery of religious matters. 
2- That it does not involve mockery or belittlement of others. 
3- That it is honest, such that no one lies in order to make the people laugh. 
4- That it does not result in harming others, like frightening someone for the sake of laughter. 

Benefits of praiseworthy humour:
1- Makes one beloved to the people, making him accepted and held dearly among them. 
2- Being sociable with friends, making them happy. 
3- Being light with the self, leaving off boredom and discontentment. 

Examples of humour from the life of the Prophet ﷺ, Companions, and Righteous Predecessors:
Anas ibn Malik, Allah be pleased with him, narrates, “A man sought a mount from the Messenger of Allah ﷺ who said, ‘I will let you ride on a she-camel's child.’ So he said, ‘Messenger of Allah, what can a she-camel's child do?’ So the Messenger of Allah ﷺ said, ‘Are camels born from other than she-camels?’” [575] Reported by Abu Dawud (4998), al-Tirmidhi (1991) and the wording is his, and Ahmad (13817). Al-Tirmidhi says, “It is sound, authentic, strange.” al-Albaniauthenticated it in Sahih Sunan al-Tirmidhi (1991). Bakr ibn `Abdillah said, “The Companions of the Prophet ﷺ used to throw melon skin at one another. At the time of seriousness, they were true men.” [576] Reported by alBukhari in al-Adab al-Mufrad (266). `Ata’ ibn al-Sa’ib said, “Sa`id ibn Jubayr would narrate to us until we wept with his admonishment, yet he would not leave our sittings until he made us laugh with his humour.” [577] al-Lata’if wa al-Zara’if, al-Tha`labi (p. 151). Among that which has been narrated from them which shows a disparagement towards humour, is what some have narrated from Mujahid, “He joked with a friend of his with a word, and that resulted in them splitting up until death.” [578] al-Amthal, Ibn Salam (p. 85).

Humour in poetry:
The poet said,
“Joke around as comfort allows; avoid
Joking which places you in bad manners.
Do not anger anyone if you joke with them.
Surely humour is right at the front of anger.” [579] Ghurar al-Khasa’is a-Wadihah, al-Watwat (p. 238, 239).