And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance. And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language. And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans?
The disciples being commanded by the Lord to tarry at Jerusalem till they be endued with power from on high, did exactly that and ten days later heaven kept the promise. The almighty Spirit of YHWH descended from on high and the impact of that day is still shaking the world today. If we ever need the power of God, it is now.