The Prophet ﷺ said, "When one of you wakes from sleep and finds wetness but does not recall having had a wet dream, he must perform the full bath. But if he recalls having had a wet dream yet finds no wetness, no bath is required of him."
حدثنا أبو بكر بن أبي شيبة حدثنا حماد بن خالد عن العمري عن عبيد الله عن القاسم
عن النبي ﷺ قال إذا استيقظ أحدكم من نومه فرأى بللا ولم ير أنه احتلم اغتسل وإذا رأى أنه قد احتلم ولم ير بللا فلا غسل عليه
No references are available.
[Its chain is daif] Abu Dawud narrated it in the Book of Purification, chapter on a man who finds moisture in his sleep, hadith 236, and Tirmidhi, hadith 113, from the hadith of Hammad bin Khalid, through the same route. Tirmidhi said, Abdullah (Umari) was declared daif by Yahya bin Saeed Qattan on account of his memory in narrating hadith.