"And the LORD spake unto Moses, saying, Speak unto the children of Israel, and say unto them, Concerning the feasts of the LORD, which ye shall proclaim to be holy convocations, even these are MY feasts" (Leviticus 23:1-2).
The feast that is upon us is called the feast of first-fruits. Also called the feast of weeks, and yet more commonly called Pentecost.
In verse 10 the feast of weeks is first mentioned.
"... ye shall bring a sheaf of the first-fruits of your harvest unto the priest: 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.And ye shall offer that day when ye wave the sheaf an he lamb without blemish of the first year for a burnt offering unto the LORD (v.10-12). On the day after the Sabbath (after the first feast) the people brought their first-fruits to be accepted before the Lord.
In John 20 and Matthew 28 it is stated that by the time Mary got to the sepulcher very early Sunday morning (the first day of the week) Jesus was already gone. Being that Christ is our Passover (1Cor.5:7), and through His blood, leaven (sin) is removed from us. He resurrected the 'morrow after the Sabbath' as the 'First-Fruits' of eternal life. In John 20:17 Jesus tells Mary not to touch Him until He goes to the Father. This is because as the First-Fruit he must be shown before the Lord and be accepted, just as the feast dictates.
"That Christ should suffer, and that he should be the first that should rise from the dead, and should shew light unto the people, and to the Gentiles" (Acts 26:23).
Now after the sheaf was waved before the Lord we are instructed to count: "ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete: Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the LORD" (Leviticus 23:15-16).