Exodus 31:15-17

Young's Literal Translation

¹⁵ `Six days is work done, and in the seventh day [is] a sabbath of holy rest to Jehovah; any who doeth work in the sabbath-day is certainly put to death,

¹⁶ and the sons of Israel have observed the sabbath; to keep the sabbath to their generations [is] a covenant age-during,

¹⁷ between Me and the sons of Israel it [is] a sign -- to the age; for six days Jehovah made the heavens and the earth, and in the seventh day He hath ceased, and is refreshed.'