Do you think Adam and Eve would not have rested with God on the very first Sabbath? If you look at the language in Genesis 2:1-3 its almost identical to the Sabbath commandment Exodus 20:8-11. Where there is no law there is no sin Romans 4:15. Did Adam and Eve sin? Then there had to be law. Genesis 26:5 shows God's commandments existed way before Mt Sinai
This doesn't answer my question. After Adam's fall, is there clear Scripture commanding to observe Sabbath?
Gen26:5 is without much detail as you know.
I'm going to post from the TWOT Hebrew Lexicon here that speaks of some of the issues with the word in Gen2; It's not my proof-text for anything but does bring up some of the language issues and inserts some theology FWIW:
2323.0 ) שָׁבַתsh¹bat( cease, desist, rest.
)2323a) שֶׁבֶת (shebet( cessation.
)2323b) שַׁבָּת (shabb¹t( Sabbath.
)2323c) שָׁבַת (sh¹bat( keep the Sabbath (Lev 25:2; Lev 23:32). Denominative verb.
)2323d) שַׁבָּתוֹן (shabb¹tôn( Sabbath observance.
)2323e) מִשְׁבָּת (mishb¹t( cessation, annihilation (Lam 1:7).
There is still some question as to whether the noun shabb¹t is derived from the verb sh¹bat, or whether shabb¹t is primary, and the verb derived from it. in any case, it should be observed that the meaning of sh¹bat is "to rest" in the sense of repose only when the verb is used in a Sabbath context (and this is confined to the Qal stem, thirteen of twenty-seven times).
The basic thrust of the verb is, when transitive, "to sever, put an end to," and when intransitive, "to desist, to come to an end." This may possibly indicate that the Sabbath is the day which 'puts a stop to' the week's work. Statistically, sh¹bat is used seventy-one times in the OT. By stem it occurs twenty-seven times in the Qal (and thirteen of these, as we indicated above, are in connection with the Sabbath observance). The translation "to cease, desist" can be illustrated in the following verses: "Day and night shall not cease" (Gen 8:22); "The seed of Israel shall cease from being a nation (Jer 31:36); "So these three men ceased to answer Job" (Job 32:1).
In the Niphal sh¹bat appears four times. It is in the Hiphil, however, that the verb appears most often: forty times. Here the meaning is "to put an end to, to cause to cease." Preponderantly in the Hiphel of sh¹bat, God is the subject of the verb. It is a favorite verb of the prophets to describe God's judgment on his people: "I will cause to cease the arrogancy of the proud" (Isa 13:11), most often in Ezekiel (ten times). Occasionally sh¹bat, with God as subject, may have a hopeful ring to it: "He makes wars cease unto the end of the earth" (Psa 46:9 [H 10]; "The Lord who has not left you without a kinsman" (Ruth 4:14).
shebet. Cessation, four times: Isa 30:7; Prov 20:3. - 2Sam 23:7. Especially the last reference has caused translation problems. BDB (992a) does not even list this 'reference under shebet. Actually the KJV is heading in the right direction when it translates "they shall be 'utterly' burned with fire." Literally we may translate, "With fire burning they will be burned without cessation," (Dahood) vs. the translation "they shall surely be burned by fire 'in the dwelling place"' (Fensham).
shabb¹t. Sabbath, the seventh day of the week. The doubling of the middle consonant may indicate that the substantive is a Piel intensive noun, although the verb sh¹bat is never used in the Piel.
Concerning the origin of the Sabbath and its possible relationship to similar institutions in ancient near eastern cultures, not a few scholars have opted for the explanation that the biblical Sabbath is an adaptation of an analogous day in Mesopotamia. Two reasons exist for the supposed comparison. One is the existence of the ûmê lemnûti "evil days." A few Babylonian texts (primarily in the seventh century B.C.) proscribe certain days of every month as "evil days" and were days on which certain types of work were prohibited. The particular days in question were: 7/14/19/21/28. But as De Vaux remarks (Al, p. 480) it is difficult to fit the seven day week into a lunar month of twenty-nine and a half days.
The second piece of evidence is the Akkadian word šab/pattu which stands for the festival of the middle day of the month or the day of the full moon. It is further identified as "the day of the appeasement of the (god's) heart" ( ûm nûh libbi) and hence a day of good omen. It is not unreasonable to posit a semantic connection between Akkadian šapattu and Hebrew shabbât. The former, we have seen, designated the middle day of the month, a day which marked a boundary and a division. It could be that Hebrew shabb¹t likewise functioned as a dividing point, separating not the month into two halves, but rather separating the month into weeks. The two words would then be analogous to each other not on the basis of Hebrew adaptation, but on the basis of a common etymology and function (AI, p. 477).
More important than the origin of the Sabbath is what we may call Sabbath theology. What is its religious significance and for what reason(s) was its observance invoked? Something of the importance of this institution can be gauged by observing that of the ten commandments the fourth commandment is treated more extensively than any of the others.
Perhaps the best procedure will be to observe the motives for observance attached to the Sabbath, a command which may be stated positively: "Six days you shall work but on the seventh you shall rest" (Exo 23:12; Exo 31:15), or negatively: "You shall not work on the Sabbath" (Exo 20:10).
In the first place Exo 20:8ff. connects observance of the Sabbath with the fact that God himself rested on the seventh day after six days of work (Gen 2:2-3). Everything God made, as recorded in Genesis, he called good. Only the Sabbath, however, he sanctified, indicating perhaps that the climax of creation was not the creation of man, as is often stated, but the day of rest, the seventh day. The Sabbath is thus an invitation to rejoice in God's creation, and recognize God's sovereignty over our time.
Secondly, we observe in Deut 5:15 that a different reason is given for observing the Sabbath. "You shall remember that you were a slave in the land of Egypt, and Yahweh your God brought you out with a mighty hand....; therefore, Yahweh your God commanded you to keep the Sabbath day." Exodus then connects the Sabbath with creation described in Genesis and Deuteronomy connects the Sabbath with deliverance from Egypt described in Exodus. Thus every Sabbath, Israel is to remember that God is an emancipator, a liberator. The early Christians were on target, it seems, when they connected the day of rest with the remembrance of Christ's resurrection. He is the one who gives freedom. Actually there is no real conflict between Deuteronomy and Exodus at this point. Whereas Deuteronomy has in view the people of the Covenant, the Exodus verses place the emphasis on the God of the covenant (AI, p. 481).
Thirdly, the Sabbath is a social or humanitarian ordinance which affords dependent laborers a day of rest: Exo 20:10, Deut 5:14-15 and Exo 23:12, "That your ox and your ass may have rest, and the son of your bondmaid, and the alien may be refreshed." Here then this commandment takes a step in the direction of making all men equal before God. As the Sabbath recalls the liberation connect this with the fact that in 1Cor 16:2 it is recorded that on the first day of the week there is a collection of money for the poor in Jerusalem?
Fourthly, the Sabbath is a sign of the covenant and in this way the Sabbath reaches into the future. The Sabbath now joins the signs of the rainbow and circumcision. The pertinent texts are Exo 31:13, 17 and Ezek 20:12, 20. This accounts for the reason that the penalty for profaning the Sabbath is death (Exo 31:14; Num 15:32-36; Jer 17:19-27). As long as Israel observes the Sabbath she affirms her loyalty to Yahweh and guarantees his saving presence. For the Christian believer these promises are fulfilled in a person, Christ. Through him we enter into God's own rest (Heb 4:1-11).
shabb¹tôn. Sabbath observance. In addition to designating the Sabbath (Exo 16:23), this word may apply to the day of atonement (Lev 16:31; Lev 23:32); the feast of trumpets (Lev 23:24); and the first and eighth days of tabernacles (Lev 23:39). The ending -on is characteiistic of abstract nouns in Hebrew such as zikk¹rôn "remembrance."
Bibliography: On shebet : Dahood, M., "Hebrew-Ugaritic Lexicography X," Bib 53:386-403, esp. p. 403. Fensham, F. C., "Exodus XXI 18-19 in the Light of Hittite Law of 10," VT 10:333-35. On shabb¹t : Armerding, H. T., "The Lord's Day Is Not Passed," CT 12:1076-78. Andreason, Niels-Erik, The Old Testament Sabbath, SBL Dissertation Series 7, 1972. idem., "Recent Studies of the Old Testament Sabbath: Some Observations," ZAW 86:453-69. Childs, B., The Book of Exodus, Westminster, 1974, pp. 412-17. Devaux, R., Al, 11, pp. 475-83. North, R., "The Derivation of Sabbath," Bib 36:182-201. Tsevat, M., "The Basic Meaning of the Biblical Sabbath," ZAW 84:447-59. Unger, Merrill F., "The Significance of the Sabbath," BS 123:53-59. Wolff, H., "The Day of Rest in the Old Testament," Lexington Theological Quarterly 7:65- 76. TDNT, VII, pp. 1-20. THAT, II, pp. 863-68. V.P.H.