Sforno on Exodus 31:13/ספורנו על שמות ל״א:י״ג

1אך את שבתותי תשמורו, even though it was I Who commanded you to build the Tabernacle and to construct all its appurtenances, and it is to serve as a residence for My presence, this commandment does not override the restrictions associated with proper observance of the Sabbath. The reason is that the Sabbath is

2אות היא ביני וביניכם, a symbol serving as a reminder of our mutual relationship. If you were to ignore this symbol by building a residence for Me on this day, there would be no point in doing so as I would not then take up residence in that Tabernacle.