Is it permissible to perform tayammum for prayer when experiencing frequent wet dreams, and there isn't enough time for ghusl and to go for Fajr prayer?

Scholars have differed regarding one who fears missing the prayer time by using water [for ablution]; the majority held that purification takes precedence, even if it leads to the expiry of the time, and this is the more correct view. The Malikis, however, held that the time takes precedence, so one should perform tayammum and pray. Therefore, in this situation, tayammum is not permissible. It is advisable to wake up early to catch the prayer on time, based on the Almighty’s saying: "Indeed, prayer has been decreed upon the believers a book [to be observed at] fixed times," and the Prophet’s (peace be upon him) saying: "Prayer [should be performed] at its appointed time."