Or HaChaim on Exodus 16:5/אור החיים על שמות ט״ז:ה׳

1 והכינו את אשר יביאו, "and they shall prepare that which they shall bring in, etc." The "bringing of the manna into the camp was in itself part of the process called "preparation." They had to do this on Friday so as not to violate the Sabbath by bringing the manna into the camp on that day. This is why Moses phrased the Sabbath legislation as including: "let no one go outside his place" (i.e. the camp, verse 29).