Acts 1:3-8

To these [men] He also showed Himself alive after His suffering [in Gethsemane and on the cross], by [a series of] many infallible proofs and unquestionable demonstrations, appearing to them over a period of forty days and talking to them about the things concerning the kingdom of God. While being together and eating with them, He commanded them not to leave Jerusalem, but to wait for what the Father had promised, “Of which,” He said,“you have heard Me speak. [John 14:16, 26; 15:26] For John baptized with water, but you will be baptized and empowered and united with the Holy Spirit, not long from now.” So when they had come together, they asked Him repeatedly, “Lord, are You at this time reestablishing the kingdom and restoring it to Israel?” He said to them, “It is not for you to know the times or epochs which the Father has fixed by His own authority. But you will receive power and ability when the Holy Spirit comes upon you; and you will be My witnesses [to tell people about Me] both in Jerusalem and in all Judea, and Samaria, and even to the ends of the earth.”