Gevurot Meyruach Hakodesh 1:10-11

And as they were gazing intently into Shomayim, while Moshiach was going — hinei — two beings, enrobed in white, had been present with them. Also, these said, Men of the Galil, why do you stand looking into Shomayim? This Rebbe, Melech HaMoshiach Yehoshua, the one having been taken up from you into Shomayim, will also come again in like manner as you saw him going into Shomayim.