Is ghusl obligatory for someone who wakes up and finds no wetness, given that semen naturally dries during sleep?

If a person wakes up and does not find any traces of semen, then ghusl (ritual bath) is not obligatory upon him, because the default is that it has not exited, and ghusl is only obligatory with certainty. However, if he finds a wet or dry trace, then ghusl becomes obligatory upon him at that time.

So, whoever wakes up and finds semen but does not recall a wet dream, then ghusl is obligatory upon him. And whoever has a wet dream but does not find semen, then ghusl is not obligatory upon him. This is based on what Aisha, may Allah be pleased with her, narrated: that the Prophet, peace and blessings be upon him, was asked about a man who finds wetness but does not recall ahm احتلامًا (a wet dream)? He said: «He should perform ghusl». And about a man who sees that he had a wet dream but finds no wetness? He said: «There is no ghusl upon him».

Ibn al-Mundhir conveyed a consensus that if a person dreams that he had a wet dream or intercourse but finds no wetness, then ghusl is not obligatory upon him. The point is to attain certainty of the exit of semen. So, if he sees the trace of dry semen after waking up, then ghusl is obligatory upon him. But if he finds no semen at all, then nothing is required of him.