Pentecost is a Jewish feast that has been celebrated since the Old Testament, being called the Feast of Harvest or the Feast of Weeks in Jewish tradition. It is mentioned in five places in the first five books — in Exodus 23, Exodus 24, Leviticus 16, Numbers 28, and Deuteronomy 16. 'Pentecost', the Greek name of this event, is also used to refer to the events in Acts 2 when the Holy Spirit intervened following Jesus' ascension to heaven.