Deut 16:9–12

16:9–12 The Passover was always celebrated on the fourteenth day of the first month (corresponding to the modern March-April). The Israelites used the lunar month, so the Passover was always on a full moon. Associated with Passover was the presentation of the first ripe sheaf of grain (Lev. 23:9). On the day following the seventh Sabbath after that presentation (Lev. 23:15, 16) was the one-day “Feast of Weeks” (v. 10), called “Pentecost” in the New Testament because of this fifty-day calculation.