I Masturbate Sometimes Without Taking a Shower Afterwards

Question :

I am a young man eighteen years of age, and for the past three years I have been masturbating. Even though I find pleasure while doing it, I always regret it afterwards and feel my conscience reproaching me. Sometimes after I masturbate I perform Ghusl, and sometimes I don't (particularly in the cold days of the winter). I don't know how many times I have prayed without having Ghusl after masturbating. During one Ramadan, I even used to masturbate during the daytime, while I was fasting. Does this affect the correctness of my fast and my prayer? Is semen pure or impure? I remember reading a Hadith wherein the Messenger of Allah stood to pray the Fajr prayer, and 'Aishah, may Allah be pleased with her, would scratch the semen off his garment (instead of washing it).

Answer:

Masturbation is an evil, practice, which the people of knowledge have declared to be forbidden. They cite the following verse as proof:
"And those who guard their chastity (i.e. private parts, from illegal sexual acts). Except from their wives or (the slaves) that their right hands possess, for then, they are free from blame; But whoever seeks beyond that, then those are the transgressors."

This habit also has many harmful effects on one's body and mind. You must, therefore, repent to Allah Almighty, and abstain from this habit in the future. You must make up those fasts wherein you masturbated while fasting, and you must make up those prayers that you prayed without performing Ghusl after masturbating. If you don't remember how many fasts and how many prayers you have to make up, make an estimate -but be sure that your estimate is sufficient to make up all of those prayers and fasts. As for semen; the correct view of the scholars is that it is pure. It is preferred to either wash the garment on which there is semen or to scratch off its stain until there remains no trace of it. However, washing it is better.

Source:
Ibn Baz
Fatawa Islamiyah, Vol. 8 Pages 303-304