Leviticus 23:12

And ye shall offer that day, when ye wave the sheaf
Besides the daily sacrifice of the morning and evening, and the additional offerings made on everyone of the seven days of the feast of unleavened bread: an he lamb without blemish of the first year, for a burnt offering
unto the Lord;
typical of the perfect and immaculate Lamb of God, whose sufferings are fitly signified by a burnt offering; and which were endured at the time he became the firstfruits of his people, and sanctified them.