Leviticus 23:15-22 KJVA
(15) And 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:
(16) Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the LORD.
(17) Ye shall bring out of your habitations two wave loaves of two tenth deals: they shall be of fine flour; they shall be baken with leaven; they are the firstfruits unto the LORD.
(18) And ye shall offer with the bread seven lambs without blemish of the first year, and one young bullock, and two rams: they shall be for a burnt offering unto the LORD, with their meat offering, and their drink offerings, even an offering made by fire, of sweet savour unto the LORD.
(19) Then ye shall sacrifice one kid of the goats for a sin offering, and two lambs of the first year for a sacrifice of peace offerings.
(20) And the priest shall wave them with the bread of the firstfruits for a wave offering before the LORD, with the two lambs: they shall be holy to the LORD for the priest.
(21) And ye shall proclaim on the selfsame day, that it may be an holy convocation unto you: ye shall do no servile work therein: it shall be a statute for ever in all your dwellings throughout your generations.
(22) And when ye reap the harvest of your land, thou shalt not make clean riddance of the corners of thy field when thou reapest, neither shalt thou gather any gleaning of thy harvest: thou shalt leave them unto the poor, and to the stranger: I am the LORD your God.
Pentecostal Day, always a Sunday, had been an annual Sabbath in Israel but, not the 7th day Sabbath.
The 7th day Sabbath and the Pentecostal Sabbath were fixed in the calendar days while the other 6 Sabbath days could have fallen on any day of the week.