Week

Boyd’s Bible Dictionary:

The division of time into weeks of seven days each dates from the earliest historic times among many and wide-apart nations

The Hebrew week began on our Sunday, their Sabbath being the seventh day or Saturday. The only day of their week they named was the Sabbath. The rest ran by numbers, as first, second, third, and so forth. Besides their week of days, Hebrews had their week of years, every seven years, and their week of seven times seven years, or year of jubilee, every fiftieth year (Gen. 8:10; 29:27¹⁰And he stayed yet other seven days; and again he sent forth the dove out of the ark; (Genesis 8:10)
²⁷Fulfil her week, and we will give thee this also for the service which thou shalt serve with me yet seven other years. (Genesis 29:27)). The “feast of weeks” corresponded with Pentecost (Ex. 23:15; 34:22¹⁵Thou shalt keep the feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty:) (Exodus 23:15)
²²And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year's end. (Exodus 34:22); Lev. 23:15-22¹⁵And 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: ¹⁶Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the Lord. ¹⁷Ye 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. ¹⁸And 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 savor unto the Lord. ¹⁹Then 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. ²⁰And 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. ²¹And 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. ²²And 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. (Leviticus 23:15‑22); Num. 28).