ACTS 1: 4-8
4 Once when he was eating with them, he commanded them, “Do not leave Jerusalem until the Father sends you the gift he promised, as I told you before. 5 John baptized with water, but in just a few days you will be baptized with the Holy Spirit.” 6 So when the apostles were with Jesus, they kept asking him, “Lord, has the time come for you to free Israel and restore our kingdom?” 7 He replied, “The Father alone has the authority to set those dates and times, and they are not for you to know. 8 But you will receive power when the Holy Spirit comes upon you. And you will be my witnesses, telling people about me everywhere—in Jerusalem, throughout Judea, in Samaria, and to the ends of the earth.”

John 14:16-17 (NIV)
16 And I will ask the Father, and he will give you another advocate to help you and be with you forever— 17 the Spirit of truth. The world cannot accept him, because it neither sees him nor knows him. But you know him, for he lives with you and will be in you.

John 14:26-27 (NIV)
26 But the Advocate, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you. 27 Peace I leave with you; my peace I give you. I do not give to you as the world gives. Do not let your hearts be troubled and do not be afraid.