Leviticus 23:10 Speak unto the children of Israel, and say unto them, When ye be come into the land which I give unto you, and shall reap the harvest thereof, then ye shall bring a sheaf of the firstfruits of your harvest unto the priest:
11 And he shall wave the sheaf before the Lord, to be accepted for you: on the morrow after the sabbath the priest shall wave it.
This offering was to be lifted up on the morning following the Israelite Sabbath, which would be the Sunday following the Saturday Sabbath. As the sun set at Passover time, the first sheaf of the harvest would have been cut and, because it would have been the eve of the Israelite Sabbath, or the Seventh Day Sabbath, the priests would have placed it in the Temple to wait to offer it on the morning after the Sabbath. This offering would come to have incredible significance.
Lenet Hadley Read explained in her book, “The Lords Holy Days, Powerful Witnesses of Truth”:
“Just as the sun set at Passover, a group of men cut down the first sheaf of the harvest. Because of the timing of the Sabbath, this would have occurred during Christ’s removal from the cross.
Thus the first sheaf of barley lay in the temple while Jesus’ body lay in the tomb.
On the morning after the Sabbath, the priests lifted up that first sheaf of the harvest as an offering to the Lord. It had always born witness, and its witness was that day fulfilled. For that very same morning Christ was lifted up in resurrection, the very first fruit of the harvest of the dead.”
1 Corinthians 15:20 But now is Christ risen from the dead, and become the firstfruits of them that slept.
Jesus Christ was literally "the firstfruit" symbolically taught to us by the first sheaf offering.