reasons why masturbation is HARAAM:
Imam Shafi’i stated that masturbation is forbidden based on the following verses from the Qur’aan (interpretation of the meaning):
"And those who guard their chastity (i.e. private parts, from illegal sexual acts). Except from their wives or (the captives and slaves) that their right hands possess, - for them, they are free from blame. But whoever seeks beyond that, then those are the transgressors." 23.5-7 Here the verses are clear in forbidding all illegal sexual acts (including masturbation) except for the wives or that their right hand possess. And whoever seeks beyond that is the transgressor.
Back to me. Well even if WE think its not haraam, who are we too debate with the conclusions that these great muslims made. Imam Shafi',Imam Malik, Imam Abu Hanifa and Imam Ibn Hanbal (may Allah have mercy on them all) all agree to its status as being haraam. I mean yeah sure, they said that we should not follow them blindy, but that we should investigate their sources and so on. But seriously, may allah forgive me for saying this but, can we even imagine our Prophet(s.a.w.s) and the sahabahs indulging in such an act? Like many scholars said, if the prophet(s.a.w.s) thought of it as ok, hed precribe masturbation to remaining chaste instead of fasting.
May Allah guide us all and have mercy on us Ameen.....
THE RULING REGARDING MASTURBATION
Masturbation is Haraam (unlawful).
This is the ruling of the four Madhaahibs viz. Maliki, Shafée, Hanafee and one riwaayah (narration) from Imaam Hanbalee. They have drawn their conclusions from the following proofs:
PROOFS FROM THE QURÃN
* Allah Taãla says: 'And those who guard their private parts from their wives and those (slave-girls) which their right-hands own - so there is no blame upon them. Then whoever seeks beyond that (which is lawful), they are the transgressors.
The intended meaning of these Aayat is clear. Allah Taãla has praised the believers for guarding their private parts from that which He has made forbidden for them. Allah has permitted them to approach their wives and slave-girls. Thereafter, these words of Allah Taãla follow: 'Whoever seeks beyond that which is lawful are oppressors who overstep from Halaal(permitted) towards Haraam (prohibited).
Hafiz ibn Katheer (RA) writes Imaam Shaafée (RA) and those who have agreed with him have concluded that masturbation is Haraam from this Aayat.' He says: 'Masturbation is excluded from these two types which Allah has made Halaal, viz. wives and slave-girls.
* Similarly, these Fuqahaa (Jurists) have drawn their conclusion from the following Aayat: 'And those who do not find the means to marry should remain chaste until Allah gives them resources by His grace.'
This Aayat shows masturbation to be Haraam because of two reasons: Firstly, in this Aayat Allah Taãla has given the command of chastity and, according to the principles of Fiqh, a command (an imperative) denotes Wujoob (incumbency, obligation). Hence to remain chaste is Waajib (compulsory) and wherever chastity is Waajib it becomes Waajib to refrain from that which is contrary to it, for example, adultery, fornication, and sodomy. This is due to the fact that obligatory chastity will not materialise except by complete refrainment from all that which is contrary to chastity.
Secondly: in this Aayat, Allah Taãla has made chastity obligatory on those who are unable to execute the command of Nikah. Here Allah Taãla has not determined any connection or link between marriage and chastity. Hence, this demands that masturbation should be Haraam. And if assuming, it was permissible, then Allah Taãla would have mentioned it at this point because this was the place of explanation. The silence maintaned by Allah Taãla with regard to it at a place which requires its explanation, denotes that masturbation is Haraam.
Imaam Qurtubi (RA) has written in the Tafseer of this Aayat: 'And when Allah Taãla has not determined any order between Nikah and chastity, then this shows that besides these two, everything else is Haraam. However, this Hurmat (unlawfulness) does not include slave-girls because another command of the Qurãn makes them Mubaah (permissible), viz. 'That which the right-hands earn (i.e. slave-girls).' Hence, in this manner an addition of slave-girl has come. Masturbation, however still remains Haraam. 'Those who seek beyond this (i.e. wives and slave-girls) are transgressors.' (Maãrij 31)
Under the Tafseer of this Aayat, Qaadhi Thanaullah Paani Patti writes: 'Imaam Baghawi has deduced from this Aayat that masturbation is Haraam.'
PROOFS FROM AHAADITH
* Similarly, the Fuqahaa have drawn their conclusion from a Hadith reported by Abdullah bin Masóod (Radhiallaahu Ánhu) in Bukhari and Muslim. He reports that Rasulullah (Sallallaahu Álayhi Wasallam) said, 'O group of youth! Whoever from among you can marry should do so because it keeps the gaze low and it protects the private parts. And he who cannot marry should make it compulsory upon himself to fast because it breaks lust.'
Nabi (Sallallaahu Álayhi Wasallam) directed the person who is incapable of bearing the burden on Nikah towards Sawm (fasting). If assuming, masturbation was permissible, Rasulullah (Sallallaahu Álayhi Wasallam) would have mentioned it at this point. Rasulullah (Sallallaahu Álayhi Wasallam) however maintained silence. Hence, this indicates that masturbation is Haraam because silence at the place of explanation gives the benefit of restriction.
* Some of the Fuqahaa have drawn their conclusion from a narration reported by Hasan bin Arfah that Nabi (Sallallaahu Álayhi Wasallam) said, 'Seven persons are such that Allah will not look at them on the Day of Qiyaamat nor will He purify them nor will He include them among the learned and Allah will enter them into Jahannam. They will enter Jahannam first except for those who repent. As those who repent Allah will accept their repentance.
1. A person who masturbates.
2. A person who performs the act of sodomy.
3. The person upon whom the act of sodomy is performed.
4. A perpetual drunkard.
5. The person who hits his parents so much that they appeal for help.
6. The person who harms his neighbours so much so that they curse him.
7. The person who commits adultery with his neighbour's wife. (Ibn Katheer vol. 5 p. 458)
Hadhrat Anas (Radhiallaahu Ánhu) narrates that Rasulullah (Sallallaahu Álayhi Wasallam) said, 'The person who performs Nikah with his hands (i.e. masturbates) is cursed. (Tafseer Mazhari vol. 12 p. 94)
SAYINGS OF OUR PIOUS PREDECESSORS WITH REGARD TO MASTURBATION
* Saéed bin Jubayr (Radhiallaahu Ánhu) narrates that Rasulullah (Sallallaahu Álayhi Wasallam) said, 'Allah Taãla will inflict a punishment on a group of people because they played with their private parts.'
* Attaa (RA) says, 'Some people will be resurrected in such a condition that their hands will be pregnant, I think they are those who masturbate.'

more justification is as follows:
1. The fiqh regarding masturbation may be found below.
2. The very meaning of Islam is submission: we submit our bodies, hearts, minds, and souls to Allah Most High, out of thankfulness for the blessing and life-giving light of His religion.
Allah tests our slavehood. Many people have 'natural' tendencies and urges towards that which Allah has declared unlawful. This is our test with Allah Most High.
Allah Most High said in the Qur'an,
"And the soul and He who perfected it
And inspired it (with conscience of) what is wrong and right for it.
He is indeed successful who purifies it,
And he is indeed a failure who stunts it." [Qur'an, 91:9-10]
The Ruling on Masturbation: Prohibitively Disliked & Sinful
Masturbation is sinful, being prohibitively disliked, because of its many personal and societal ill-effects that are known and recognised in sane traditional societies and by balanced people the world over.
As for modern 'expert' opinions that there is 'nothing wrong with it,' these are the opinions of the same people who see nothing wrong with fornication, nudity, and most other personal and social depravity.
The early Muslims used to say, "The one who weds his hand is accursed." (Fath al-Qadir)
Its prohibition was established by Allah Most High's words, "Those who guard their private parts, except from their spouses..." [Qur'an, 23: 5]
Thus, the general ruling regarding sexual activity is that it is impermissible, except through the particular channel that Allah permitted, out of His tremendous wisdom and mercy for His creation.
The rulings of the Shariah are for the worldly and eternal benefit of humanity, as a manifestation of the tremendous mercy of Allah, for Allah Himself is absolutely free of any need. Rather, it is we who need guidance, to give true joy and illumination to our lives in this world and the next.

[derived from: Ibn Abidin's Hashiya, al-Lakhnawi's Naf` al-Mufti wa'l Sa'il, and al-Nahlawi's Durar al-Mubaha, Kamal ibn al-Humam's Fath al-Qadir]
As for the fast: masturbation that leads to ejaculation invalidates the fast.
[Masturbation]
Regarding the position of the Hanbali madhhab regarding masturbation, Kashshaf Al-Qina` (6:125) indicates that whoever masturbates out of fear of committing fornication or fear for their body has done nothing wrong and is not punished if (and only if) he is unable to marry--even a slave girl--and if he was able to marry it is unlawful and he is entitled to punishment. This applies to men and women equally. The reason given is out of necessity (durara), which was mentioned above.
Please note that one of the conditions is that the person in question not even be able to marry a slave girl who is someone else's property, which means that any children would be born into slavery. What is significant here is that having your children born slaves is better than masturbation. This is not a light matter.
Also please note that provided there is someone that one could marry, masturbation is unlawful. No where does it say that the spouse has to be from the same culture, has to be a perfect match, or anything like that. As long as there is an upright marriageable Muslim it is unlawful, and if not punished in this world it surely is in the next. It goes back to availability, not economic stability, diploma, beauty, hair color, nationality, ethnicity or cultural origins. There are a lot of people who mix up necessity, need and luxury. This ruling is about necessity.
In closing, we know that divorce is the most despicable of lawful things to Allah, whereas fornication is haram. Parents should keep this in mind before putting so many conditions that must be met before marriage, especially since anything that leads to the unlawful is itself unlawful.
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I would recommend any person who is involved in mastubation to keep roza(fast) because it controls once sexual desires. If you think you cannot fast , then you should do some exercise and no doubt exercise does keeps ones sexual desires under control.
Their are many side effects of mastubation and their is a medical report which throws light on the symptoms of mastubation.
Some of the dangerous side effects of mastubation:
1. It badly effects ones memory and reduces it to great extent.
2. The eyesight of a person drops due to weakness of memory.
3. It causes problems in digestive system
4. The bones and joints become weak
5. A person loses sensations.
I have mentioned some of the common side effects of mastubation and I hope my brothers will avoid doing it. Believe me brothers i have seen some people who have destroyed their future by getting involved in these kinds of bad activities, it is just like drug addiction, If any person who thinks that if he does mastubation once a week or month then it will not harm him but this is not true because most of the people who do excessive mastubation are those who use to do it once a month but later they got into its habbit and ruined their lives.
I would recommend those who want to get ride of mastubation, to do exercise when ever you feel like mastubating, it surely does controls sexual desires, and divert your attention from mastubation as soon as this evil strikes your mind.