Matthew 26:17-19 “Now on the first day of Unleavened Bread the disciples came to Jesus, saying, “Where will you have us prepare for you to eat the Passover?” 18 He said, “Go into the city to a certain man and say to him, ‘The Teacher says, My time is at hand. I will keep the Passover at your house with my disciples.’” 19 And the disciples did as Jesus had directed them, and they prepared the Passover.”

Acts 1:12-14 “Then they returned to Jerusalem from the mount called Olivet, which is near Jerusalem, a Sabbath day's journey away. 13 And when they had entered, they went up to the upper room, where they were staying, Peter and John and James and Andrew, Philip and Thomas, Bartholomew and Matthew, James the son of Alphaeus and Simon the Zealot and Judas the son of James. 14 All these with one accord were devoting themselves to prayer, together with the women and Mary the mother of Jesus, and his brothers.”

Jesus promised:
John 14:15-17 “If you love me, you will keep my commandments. 16 And I will ask the Father, and he will give you another Helper, to be with you forever, 17 even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you.”

James 4:8 “Draw near to God, and he will draw near to you. Cleanse your hands, you sinners, and purify your hearts, you double-minded.”

Jeremiah 29:13 “ You will seek me and find me, when you seek me with all your heart.”

You can find this first account of the UPPER ROOM usage referenced in all four Gospels.
Matthew 26:1-29
Mark 14:12-25
Luke 22:7-20
John 13-17