...and he "rested" on the seventh day

We have therefore, to accept, without reserve, the statement of the Fourth Commandment that the Sabbath primarily originated in the extraordinary fact that “in six days the Lord made heaven and earth, and on the seventh day he rested, and was refreshed” (Exod. 31:17). The idea of the “refreshment” of Deity has given the scoffer a theme of jest. There is no cause for jest at all when the matter is understood in the light of the facts hinted at a little way back. The angels, as the instruments and users of the energy employed in the work, are not to be thought of as inexhaustible Deity. Their power, though inconceivably higher than human, must be subject to a limitation unknown to “the Creator of the ends of the earth, who fainteth not, neither is weary”. It is not, therefore, an inconceivable or anomalous idea that after the stupendous power put forth in the re-organization of this sublunary creation in six days, the Elohim should have welcomed the suspension of creative work on the seventh day, as affording an opportunity of replenishing spent energy by re-absorption from the Eternal Fountain. This, at all events, is the Scripturally alleged occasion of the appointment of the seventh day of the week as a Sabbath of rest. “And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made.”

Roberts, R. (1987). The Law of Moses (electronic ed.). Birmingham, UK: The Christadelphian.