Rashi on Exodus 20:11/רש"י על שמות כ׳:י״א

1וינח ביום השביעי AND HE RESTED ON THE SEVENTH DAY — If one may say so, He recorded rest about Himself (recorded that He rested) to teach from this an inference à fortiori as regards a human being whose work is performed only by labour and toil — that he should rest on the Sabbath day (Mekhilta).

2ברך… ויקדשהו HE BLESSED … AND SANCTIFIED IT — He blessed it through the Manna by giving a double portion on the sixth day — “double bread”; and He sanctified it through the Manna in that on it none fell (Mekhilta; cf. Rashi on Genesis 2:3).