Is Tahyatul Wudhu Salaat permissible before Fajr and before Asr?

Answer

If 'before Fajr' you mean before the time of Fajr has entered, that is, while it is still time for Tahajjud and Sehri, then Tahyatul Wudhu is permissible. But, if you mean before Fajr Salaat, that is after Fajr time has begun, then it is not permissible to perform Tahyatul Wudhu or any Nafl Namaaz in the entire duration of Fajr time, whether before or after Fajr Namaaz. It is permissible to perform Tahyatul Wudhu or any Nafl Salaat before the Fardh of Asr, but not after the Fardh of Asr.