Numbers 28:3-10 (HCSB) And say to them: This is the fire offering you are to present to the LORD: “Each day ⌊present⌋ two unblemished year-old male lambs as a regular burnt offering. Offer one lamb in the morning and the other lamb at twilight, along with two quarts of fine flour for a grain offering mixed with a quart of olive oil from crushed olives. It is a regular burnt offering established at Mount Sinai for a pleasing aroma, a fire offering to the LORD. The drink offering is to be a quart with each lamb. Pour out the offering of beer to the LORD in the sanctuary area. Offer the second lamb at twilight, along with the same kind of grain offering and drink offering as in the morning. It is a fire offering, a pleasing aroma to the LORD. “On the Sabbath day ⌊present⌋ two unblemished year-old male lambs, four quarts of fine flour mixed with oil as a grain offering, and its drink offering. It is the burnt offering for every Sabbath, in addition to the regular burnt offering and its drink offering.
In Terrance O'Hare's excellent book The Sabbath Complete, he notes (pages 92-94) this requirement for priestly work on the weekly Sabbath that serves as a type that is grounded in the 7th day sacrifice of animals by YHWH to provide clothing for the first sinners, pointing to the provision for sinners to be covered by the blood of the Lamb Who was to come. O'Hare observes, "A Sabbath without sacrifices amounts to a presumptuous mockery of the symbolism inherent it observance. The inconsistency of Sabbatarianism is greatest at this juncture. Sabbatarians agree that Christ fulfilled the sacrificial duties of the Sabbath and that continuing to offer bloody sacrifices denigrates the sacrificial act of Jesus Christ upon the cross. Yet they state that His death did nothing to the remaining Sabbath laws. Like modern Jews without the temple, Sabbatarians think their "mitvahs" are enough to present the Sabbath to God."
The near complete disconnect between the Reformed confessions teaching on the weekly Sabbath and the biblical description and requirements for that day is profound. These documents claim the continuing practice of the weekly Sabbath but have introduced a faux-Sabbath built not on Scripture, but upon man's imagination.