Question:

For what reason is the small ablution (Wudu’) sufficient for urination and defecation, while the ejaculation requires the large ablution (Ghusl)?

Answer:

Al-Fadl Ibn Shadhan reported that Imam Ar-Rida (a.) said: “The small ablution (Wudu’) was required only for what came out solely from both ends, and from sleep. One was not commanded the great ablution (ghusl) from this uncleanness (najasah) as one was commanded the great ablution for the state of abstinence (janabah), for this is a continuous matter in which the creature is unable to perform the great ablution (ghusl) every time it is affected, and God does not hold a soul responsible except for what it is able to perform, and the state of abstinence (janabah) is not a continuous matter. It is only a lust that strikes the one who desires it, and its fast progress, and its delay is possible to one for three days or less or more, although it is not so with your matter. One has only been commanded the great ablution (ghusl) from the state of abstinence (janabah), and one has not been commanded the great ablution for the excretion, though it is more impure and dirty than the state of abstinence (janabah), for the state of abstinence emanates from man himself and is a thing that comes forth from his whole body, and the excretion does not come from man himself, but is only food that comes in by one way and comes out by another way.” [Wasa’il-ush-Shi’ah by Al-Amili, Volume 2 Page 180]

عن الفضل بن شاذان عن الإمام الرضا عليه السلام قال: إنما وجب الوضوء مما خرج من الطرفين خاصة، ومن النوم (إلى أن قال:) وإنما لم يؤمروا بالغسل من هذه النجاسة كما امروا بالغسل من الجنابة، لان هذا شيئ دائم غير ممكن للخلق الاغتسال منه كلما يصيب ذلك، ولا يكلف الله نفسا إلا وسعها، والجنابة ليس هي أمرا دائما، إنما هي شهوة يصيبها إذا أراد، ويمكنه تعجيلها وتأخيرها الايام الثلاثة والاقل والاكثر، وليس ذينك هكذا، قال: وإنما امروا بالغسل من الجنابة ولم يؤمروا بالغسل من الخلا وهو أنجس من الجنابة وأقذر، من أجل أن الجنابة من نفس الانسان وهو شيئ يخرج من جميع جسده، والخلاء ليس هو من نفس الانسان، إنما هو غذاء يدخل من باب ويخرج من باب