Is it permissible to joke by cursing and insulting among family members, such as saying: "You are crazy" or "a dog" or "a donkey"? And is it permissible to joke by hitting or wrestling among friends? Are there specific regulations for this, or any sayings of scholars concerning it?

A Muslim's life should be built upon seriousness, diligence, and the utilization of time to increase good deeds and prepare for the hereafter. However, jesting is permissible at times, provided it adheres to truth and leads only to good. Indeed, the Prophet, peace and blessings be upon him, would jest with his companions but would speak nothing but the truth. Jesting should serve a noble purpose, such as entertaining companions or relaxing oneself, and not for wasting time. It should be in proportion, like salt in food.

One must avoid jesting with words that are uncouth and contravene the words of Allah Almighty: ("And speak to people good words") and ("Nor call each other by [offensive] nicknames"), for such words are a means for Satan to sow enmity and hatred, and are considered hurtful and abusive. A true believer is not one who slanders, curses, or is obscene or vulgar.

As for physical jesting, such as wrestling or light striking, it is permissible if it does not typically cause harm, does not involve humiliation, is consented to by the other party, and occurs occasionally at appropriate times. However, if it causes harm, injury, or humiliation, it is not permissible, as it may lead to enmity or injuries. Lawful jesting is that in which Muslims are safe from the tongue and hand of others, and it must have controls that prevent harm to others.