The prophet Zechariah foretold of the coming of the LORD God, an event which would take place at the Mount of Olives:
On that day, He will set His feet on the Mount of Olives, near Jerusalem on the east; and the Mount of olives shall split across from east to west, and one part of the Mount shall shift to the north and the other part to the south, a huge gorge. And the valley in the Hills shall be shall be stopped up, for the Valley of the Hills shall reach to Azal; it shall be stopped up as it was stopped up as a result of an earthquake in the days of King Uzziah of Judah. - And the LORD my God, with all the holy beings, will come to you. (Zechariah 14:4-5 NJPS)
The heavenly witnesses to Jesus ascending into heaven told the disciples He would return:
6 So when they had come together, they asked him, “Lord, will you at this time restore the kingdom to Israel?” 7 He said to them, “It is not for you to know times or seasons that the Father has fixed by his own authority. 8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.” 9 And when he had said these things, as they were looking on, he was lifted up, and a cloud took him out of their sight. 10 And while they were gazing into heaven as he went, behold, two men stood by them in white robes, 11 and said, “Men of Galilee, why do you stand looking into heaven? This Jesus, who was taken up from you into heaven, will come in the same way as you saw him go into heaven.” 12 Then they returned to Jerusalem from the mount called Olivet, which is near Jerusalem, a Sabbath day's journey away. (Acts 1 ESV)