Praise be to Allah.
Ghusl may be waajib (obligatory) or it may be sunnah and mustahabb. The scholars (may Allah have mercy on them) have described all cases, and their comments may be divided into three categories:
1 – Cases in which ghusl is required according to consensus:
(i)Emission of maniy (semen) even if it is not through intercourse.
It says in al-Mawsoo’ah al-Fiqhiyyah (31/195):
The fuqaha’ are unanimously agreed that emission of maniy (semen) is one of the things that make ghusl obligatory. Al-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 hadeeth of Abu Sa’eed 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 al-Nawawi, is that it becomes obligatory to do ghusl with water if gushing water is emitted, i.e., maniy. End quote.
(ii)Meeting of the two circumcised parts when the tip of the penis disappears completely in the vagina, even if no ejaculation takes place.
(iii)and (iv) Menstruation and nifaas (post partum bleeding)
In al-Mawsoo’ah al-Fiqhiyyah (31/204) it says:
The fuqaha’ are unanimously agreed that menstruation and nifaas are among the things that make ghusl obligatory. Ibn al-Mundhir, Ibn Jareer, al-Tabari and others 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]. End quote
2 – Cases in which ghusl is not required according to consensus, but it is mustahabb
(i)Every time one is going to meet people – it is mustahabb to do ghusl beforehand.
Al-Baghawi (may Allah have mercy on him) said: It is mustahabb 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. Al-Nawawi (may Allah have mercy on him) said in al-Majmoo’ (2/233): It is Sunnah for everyone according to consensus, men, women and children, because it is part of adoring oneself. End quote.
See also 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-Haraam, before stoning the Jamaraat on the days of tashreeq, and other places where people gather to do acts of worship or gather according to their customs.
(ii)When undergoing any physical change.
Al-Muhaamili – who was a Shaafa’i faqeeh – said: It is mustahabb to do ghusl every time one undergoes a physical change.
For example, the fuqaha’ stated that it is mustahabb 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-Majmoo’ (2/235, 234).
(iii)For some acts of worship, such as doing ghusl when entering ihraam.
The Prophet (peace and blessings of Allah be upon him) did ghusl before changing into his ihraam garments. Narrated by al-Tirmidhi, 830. The fuqaha’ stated that it is mustahabb to do ghusl for tawaaf al-ziyaarah and tawaaf al-wadaa’ (farewell tawaaf), and on Laylat al-Qadar. When Ibn ‘Umar 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-Bukhari (1478) and Muslim (1259).
3 – Ghusl concerning which the scholars differed, and which view is more likely to be correct
(i)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).
(ii)Ghusl after washing the deceased.
The scholars differed concerning this, based on their differences about the hadeeth 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 Dawood (3161) and al-Tirmidhi (993), who said it is a hasan hadeeth. Imam Ahmad said in Masaa’il Ahmad by Abu Dawood (309): No hadeeth is proven concerning this.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said in al-Sharh al-Mumti’ (1/411): The correct view is that it is mustahabb. End quote.
See also question no. 6962.
(iii)Ghusl on Fridays
Al-Nawawi said in al-Majmoo’ (2/232): It is Sunnah according to the majority, and some of the salaf regarded it as obligatory. End quote.
The correct view is that which was favoured by Shaykh al-Islam Ibn Taymiyah 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. End quote.
(iv)When a kaafir becomes Muslim
The Maalikis and Hanbalis are of the view that if a kaafir becomes Muslim, ghusl is required, because of the report narrated by Abu Hurayrah (may Allah be pleased with him) that Thumaamah ibn Athaal (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 ‘Aasim 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 janaabah, so ghusl is required for that reason.
The Hanafis and Shaafa’is are of the view that it is mustahabb for a kaafir to do ghusl when he becomes Muslim even if he is not junub, 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 kaafir becomes Muslim when he is junub, then he has to do ghusl. Al-Nawawi (may Allah have mercy on him) said: This was stated by al-Shaafa’i, and the majority of our companions are agreed on that. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said in al-Sharh al-Mumti’ (1/379): In order to be on the safe side he should do ghusl. End quote.
And Allah knows best.