Exodus 16:25 - Ellicott's Commentary On The Whole Bible

To day is a sabbath. — That is to say, a rest By these words the Sabbath was either instituted, or re-instituted, and became thenceforth binding on the Israelites. Its essential character of a weekly “rest” was at once assigned to it — (1) by its name; (2) by God’s resting on it from His self-imposed task of giving the manna; and (3) by the rest which the absence of manna on the seventh day imposed on the people. Thus the way was prepared for the stringent law of Sabbath observance laid down in the fourth commandment.