Sayyiduna Abu Sa'id (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "The fast is not broken for one who vomits, nor for one who has cupping done, nor for one who has a wet dream."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8272