When Is Ghusl Not Required?
Question

Is bath (Ghusl) obligatory after wet dreams or do you have to do it only after sexual intercourse? What are the other conditions when a Muslim has to take a bath (Ghusl)?
Praise be to Allah.Ghusl may be obligatory or it may be sunnah and encouraged. The scholars (may Allah have mercy on them) have described all cases, and their comments may be divided into three categories: 
Cases in which Ghusl is required according to consensus: 

Emission of Maniy (semen) even if it is not through intercourse.

It says in Al-Mawsu`ah Al-Fiqhiyyah (31/195): 
“The jurists unanimously agreed that emission of Maniy (semen) is one of the things that make Ghusl obligatory. An-Nawawi narrated that there was consensus on this point. No distinction is made between men and women, or whether one is asleep or awake. The basic principle concerning that is the Hadith of Abu Sa`id Al-Khudri (may Allah be pleased with him) according to which the Prophet (peace and blessings of Allah be upon him) said: “Water is for water (i.e., Ghusl must be done when semen is emitted).” (Narrated by Muslim, 343). What this means, as was stated by An-Nawawi (may Allah have mercy on him), is that it becomes obligatory to do Ghusl with water if gushing water is emitted, i.e., semen.” Please see also questions no. 6010 , 12317  and 47693 . 

 Meeting of the two circumcised parts when the tip of the penis disappears completely in the vagina, even if no ejaculation takes place. Please see questions no. 7529  and 36865 . 
Menstruation and postpartum bleeding.

In Al-Mawsu`ah Al-Fiqhiyyah (31/204) it says:  
“The jurists unanimously agreed that menstruation and postpartum bleeding are among the things that make Ghusl obligatory. Ibn Al-Mundhir, Ibn Jarir, At-Tabari and others  (may Allah have mercy on them) narrated that there was consensus on this point. The evidence that Ghusl is required following menses is the verse in which Allah says (interpretation of the meaning): 
“They ask you concerning menstruation. Say: that is an Adha (a harmful thing for a husband to have a sexual intercourse with his wife while she is having her menses), therefore, keep away from women during menses and go not unto them till they are purified (from menses and have taken a bath). And when they have purified themselves, then go in unto them as Allah has ordained for you” [Al-Baqarah 2:222]” 
Cases when Ghusl is not required according to consensus, but it is encouraged 

Every time one is going to meet people – it is encouraged to do Ghusl beforehand.

Al-Baghawi (may Allah have mercy on him) said: 
“It is encouraged for the one who wants to meet with people to do Ghusl, clean himself and perfume himself. That includes doing Ghusl on the two `Eids. An-Nawawi (may Allah have mercy on him) said in Al-Majmu` (2/233): "It is encouraged for everyone according to consensus, men, women and children, because it is part of adoring oneself.” Please see question no. 48988 . 
That also includes doing Ghusl before the eclipse prayer, prayers for rain (Istisqa’), standing in `Arafah, doing Ghusl in Al-Mash’ar Al-Haram, before stoning the Jamarat on the days of Tashriq, and other places where people gather to do acts of worship or gather according to their customs. 

When undergoing any physical change.

Al-Muhamili (may Allah have mercy on him) – who was a Shafi`i jurist – said: “It is encouraged to do Ghusl every time one undergoes a physical change.”  
For example, the jurists stated that it is encouraged for the one who went insane or fell unconscious to do Ghusl when he recovers, and to do Ghusl after cupping, after entering the Hammam and so on, because the Ghusl will remove anything that has gotten onto the body and will restore it to a natural state.” (See Al-Majmu`, 2/235, 234) 

For some acts of worship, such as doing Ghusl when entering Ihram .

The Prophet (peace and blessings of Allah be upon him) did Ghusl before changing into his Ihram garments.  (Narrated by At-Tirmidhi, 830) 
The jurists stated that it is encouraged to do Ghusl for Tawaf Az-Ziyarah and Tawaf Al-Wada` (farewell Tawaf), and on Laylat Al-Qadar. When Ibn ‘Umar (may Allah be pleased with him) entered Makkah he would do Ghusl, and he said that the Prophet (peace and blessings of Allah be upon him) used to do that. (Narrated by Al-Bukhaari,  1478 and Muslim, 1259)
Cases where scholars differed on the obligation of Ghusl

Ghusl for the deceased.

The majority of scholars are of the view that death is one of the things that make Ghusl obligatory, because the Prophet (peace and blessings of Allah be upon him) said to the women when his daughter died: “Wash her three times or five or more than that.” (Narrated by Al-Bukhaari, 1253 and Muslim, 939) 

Ghusl after washing the deceased.

The scholars differed concerning this, based on their differences about the Hadith that was narrated concerning it. It was narrated from Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said: “Whoever has washed a dead person, let him do Ghusl.” (Narrated by Ahmad, 2/454, Abu Dawud, 3161 and At-Tirmidhi, 993, who said it is a sound Hadith. Imam Ahmad said in Masa’il Ahmad by Abu Dawud, 309: No Hadith is proven concerning this)  
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) said in Ash-Sharh Al-Mumti’ (1/411): “The correct view is that it is encouraged.” Please also see question no. 6962 . 

Ghusl on Fridays

An-Nawawi said in Al-Majmu` (2/232): “It is encouraged according to the majority, and some of the salaf regarded it as obligatory.”
The correct view is that which was favoured by Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) in Al-Fataawa Al-Kubra (5/307): “It is obligatory to do Ghusl on Fridays for one who is sweaty or has an odour that may offend others.”

When a disbeliever becomes Muslim

The Malikis and Hanbalis are of the view that if a disbeliever becomes Muslim, Ghusl is required, because of the report narrated by Abu Hurayrah (may Allah be pleased with him) that Thumamah ibn Athal (may Allah be pleased with him) became Muslim, and the Prophet (peace and blessings of Allah be upon him) said: “Take him to the garden of Banu so and so and tell him to do Ghusl.” And it was narrated that when Qays ibn `Asim became Muslim, the Prophet (peace and blessings of Allah be upon him) told him to do Ghusl with water and lotus leaves. And in most cases the new Muslim will not be free of Janabah (ritual impurity due to intercourse), so Ghusl is required for that reason.  
The Hanafis and Shafi`is are of the view that it is encouraged for a disbeliever to do Ghusl when he becomes Muslim even if he is free of Janabah, because many people became Muslim and the Prophet (peace and blessings of Allah be upon him) did not tell them to do Ghusl. If a disbeliever becomes Muslim when he is in the state of Janabah, then he has to do Ghusl. 
An-Nawawi (may Allah have mercy on him) said: “This was stated by Al-Shafi`i, and the majority of our companions agreed on that.”
Shaykh Ibn ‘Uthaymien (may Allah have mercy on him) said in Ash-Sharh Al-Mumti` (1/379): “In order to be on the safe side he should do Ghusl.”
And Allah knows best.