A quote of a reference book states: Jesus did not specifically state how often the Memorial of his death was to be kept. However, he instituted it on the date of the Jewish Passover, which was replaced among his disciples by the Memorial of Christ’s death. The Passover was an annual event, celebrated on Nisan 14. Similarly, the Jewish Festival of Unfermented Cakes, the Festival of Weeks (Pentecost), the Festival of Booths, or Ingathering, and the Day of Atonement were all held once a year.