The question was asked, How did the Israelites know they were to keep every Sabbath day holy?
Because the Sabbath was the institution. It was not just something God told them to do and they did it on Sabbath. Sabbath was the institution. First day is not the institution, L.S. is, and they did it on the first day on this occasion. Exodus 31:12, 16 – And the LORD spake unto Moses, saying, Wherefore the children of Israel shall keep the Sabbath, to observe the Sabbath throughout their generations, for a perpetual covenant. That is how I know every Sabbath, because he said, keep it (Sabbath) throughout the generations. That teaches every Sabbath. Sabbath was a day that was to be kept. The day itself was the institution. In the institution of the L.S. Jesus mentioned nothing about a day to do it on. Pat makes a similar argument on the Passover. Exodus 12:11, 14 – And thus shall ye eat it; with your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste: it is the LORDs Passover. And this day (the 14th day of the 1st month) shall be unto you
