Leviticus 23:15-17

‘You shall count from the day after the Sabbath, from the day when you brought in the sheaf (tied bundle of grain) of the wave offering; there shall be seven complete Sabbaths (seven full weeks). You shall count fifty days to the day after the seventh Sabbath; then you shall present a new grain offering to the LORD. You shall bring in from your places two loaves of bread as a wave offering, made from two-tenths of an ephah of fine flour; they shall be baked with leaven as first fruits to the LORD.