THE DEFINITE DATE OF THE ARRIVAL OF THE MOSHIACH [HAZRAT MAHDI (AS)] IS SEALED UNTIL THE TIME OF THE END

The first thing you must know is that it is impossible for a person to ever know the definite date [of the arrival of the Moshiach (Hazrat Mahdi (as)], as Daniel explained and said, “Because the matters are obscured and sealed [until the time of the end]” (Daniel 12:9).

(Rambam, Iggeres Teiman 3)