Mark 13:29-33

Even so, you too, when you see these things happening, know [for certain] that He is near, right at the door. I assure you and most solemnly say to you, this generation [the people living when these signs and events begin] will not pass away until all these things take place. Heaven and earth [as now known] will pass away, but My words will not pass away. But of that [exact] day or hour no one knows, not even the angels in heaven, nor the Son [in His humanity], but the Father alone. “Be on guard and stay constantly alert [and pray]; for you do not know when the appointed time will come.