Leviticus 23:15-16
Read Leviticus 23 in full →The Feast of Weeks
15‘aYou shall also count for yourselves from the day after the sabbath, from the day when you brought in the sheaf of the wave offering; there shall be seven complete sabbaths. 16‘You shall count fifty days to the day after the seventh sabbath; then you shall bring a anew grain offering near to Yahweh.