Rashi on Exodus 16:29/רש"י על שמות ט״ז:כ״ט

1ראו SEE with your very eyes (i. e. the word is used literally and not figuratively in the sense of “consider”) that the Lord in His glory (i. e. the Lord Himself) admonishes you regarding the Sabbath, for, behold, a miracle is performed for you on the eve of every Sabbath in that He gives you then bread for two days.

2שבו איש תחתיו ABIDE YE EVERY MAN IN HIS PLACE (lit., beneath himself) — From here the Sages derived a support for the permission that a person who has gone beyond the Sabbath limit may move within a space of four cubits (Mekhilta; Eruvin 51a).

3אל יצא איש ממקמו LET NO MAN GO OUT OF HIS PLACE — These are the 2,000 cubits of the Sabbath limit (Mekhilta); but this is not expressly mentioned here, because the command relating to the Sabbath limits is only an institution of the Sopherim. The text itself was really spoken about those who gathered the Manna (i. e., it does not constitute a prohibition regarding the Sabbath for all men and at all periods but was intended to forbid anyone to go out into the field to gather the Manna; cf. Sotah 30b).