Deuteronomy 16:9 in the King James Version
Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the corn.
Context
8 Six days you shall eat unleavened bread. On the seventh day shall be a solemn assembly to the LORD your God. You shall do no work.
9 You shall count for yourselves seven weeks. From the time you begin to put the sickle to the standing grain you shall begin to count seven weeks.
10 You shall keep the feast of weeks to the LORD your God with a tribute of a free will offering of your hand, which you shall give according to how the LORD your God blesses you.