You can find more about Pentecost here and here.
"In Italy it was customary to scatter rose leaves from the ceiling of the churches to recall the miracle of the fiery tongues; hence in Sicily and elsewhere in Italy Whitsunday is called Pascha rosatum."
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. (Act 2:1-4)
To the chief Musician, to Jeduthun, A Psalm of David.
Truly my soul waiteth upon God: from him cometh my salvation. He only is my rock and my salvation; he is my defence; I shall not be greatly moved.
How long will ye imagine mischief against a man? ye shall be slain all of you: as a bowing wall shall ye be, and as a tottering fence. They only consult to cast him down from his excellency: they delight in lies: they bless with their mouth, but they curse inwardly. Selah.
My soul, wait thou only upon God; for my expectation is from him. He only is my rock and my salvation: he is my defence; I shall not be moved. In God is my salvation and my glory: the rock of my strength, and my refuge, is in God.
Trust in him at all times; ye people, pour out your heart before him: God is a refuge for us. Selah.
Surely men of low degree are vanity, and men of high degree are a lie: to be laid in the balance, they are altogether lighter than vanity. Trust not in oppression, and become not vain in robbery: if riches increase, set not your heart upon them.
God hath spoken once; twice have I heard this; that power belongeth unto God. Also unto thee, O Lord, belongeth mercy: for thou renderest to every man according to his work.