The Sabbath was understood to be the unique sign of the covenant (31:13, 16, 17; see also 20:8–11; Isaiah 58:13–14; Jeremiah 17:21–27; Nehemiah 13:15–22). The Sabbath also played an important role in God’s plan to make his people holy. Holy refers to being set apart for God’s special use and sharing his character (Exodus 31:13, 14, 15).
By resting on the Sabbath, the people showed that they belonged to him. They stopped their own work on that day (31:15, 17).
This rest was also a practical way to show trust in God. It showed that they depended on him to provide what they needed (see 20:8–11 and study notes).