Shabbos light radiating through the week

בפסוק ויסעו מהר ה' דרך שלשת ימים כו'.

On the verse, "And they journeyed from the mountain of Hashem a distance of three days…" (Bamidbar 10:33).

The Sefas Emes opens with Bnei Yisrael's first journey from Har Sinai, traveling a three-day distance.

כי הנה כל המסעות היו להלחם עם הסט"א כמ"ש ויהי בנסוע כו' קומה כו' ויפוצו אויבך והוא בחי' ימי המעשה.

For behold, all the journeys were to wage war with the sitra achra (the "other side"), as it is written, "And it was, when the ark traveled… 'Arise [Hashem] and let Your enemies be scattered'" — and this is the aspect of the weekdays (yemei ha-ma'aseh).

Every "journey" in the wilderness was a campaign against the forces of impurity — hence the prayer "Arise Hashem, scatter Your enemies" at each departure. Travel and struggle correspond to the workweek, the time of effort and battle.

ובנוחה הוא בחי' שבת.

And in resting (u-venuchoh), it is the aspect of Shabbos.

The verse's counterpart — "and when it rested" he would say "Return, Hashem" — corresponds to Shabbos, the day of menuchah.

ולעולם כן הוא המסע בימי המעשה ומנוחה בש"ק.

And it is always so: the journeying is in the weekdays, and the rest is on Shabbos Kodesh.

This is a permanent pattern of avodah: the week is for advancing and struggling, Shabbos for rest and arrival.

ואיתא כי יש ג' ימים דקמי שבתא וג"י דבתר שבתא שהארת השבת מתקיים ג' ימים וגם ג' ימים מקמי שבתא מה שמכינים אל השבת והוא ג"כ כח השבת שמאיר לעניו ולאחריו.

And it is stated that there are three days before Shabbos and three days after Shabbos: that the illumination of Shabbos endures for three days [afterward], and also the three days before Shabbos are what one prepares toward Shabbos — and this too is the power of Shabbos, which shines before it and after it.

Halachically the week splits around Shabbos: the three days following it still carry Shabbos's afterglow, and the three days preceding it are devoted to preparing for it. The light of Shabbos radiates in both directions across the whole week.

וכ"כ במכילתא שמור וזכור מלפניו ומלאחריו משל לזאב כו' ע"ש.

And so it is written in the Mechilta: "Guard" and "Remember" — from before it and from after it — a parable of a wolf [that attacks from before and behind]; see there.

The Mechilta presents shamor and zachor as protecting Shabbos from both sides, like guarding against a wolf that can strike from front or back — reflecting that Shabbos's influence extends both before and after the day itself.

וז"ש ויסעו מהר ה' דרך שלשת ימים הוא ג' אחר שבת.

And this is the meaning of "and they journeyed from the mountain of Hashem a distance of three days" — these are the three days after Shabbos.

The "three days" of journeying away from Har Sinai correspond to the three days after Shabbos, when one carries the Shabbos light forward into the workweek.

וארון ברית ה' נוסע כו' דרך שלשת ימים כו' הוא ג' ימים דקמי שבתא.

And "the Ark of the covenant of Hashem traveled… a distance of three days…" — these are the three days before Shabbos.

The Aron's going before them a three-day distance corresponds to the three days leading up to Shabbos, the days of preparation.

וז"ש לתור להם מנוחה הכנה אל השבת הבאה.

And this is the meaning of "to seek out for them a resting place" — preparation toward the coming Shabbos.

"To seek out a menuchah for them" means preparing the way toward the next Shabbos — the rest that the three preceding days lead up to.

וכן איתא בגמ' שתיקן עזרא שלא להיות ג' ימים בלי תורה הרי שקריאת התורה מאיר

And so it is stated in the Gemara that Ezra enacted that there should not be three days without Torah — thus showing that the reading of the Torah illuminates [in both directions].

Chazal relate that Ezra established public Torah reading on Monday and Thursday so that no three days pass without Torah. This too reflects the three-day spans around Shabbos: the reading of the Torah, like Shabbos itself, casts its light forward and backward across the week.

Summary: The desert journeys ("traveling") represent the weekday avodah of battling the sitra achra, while "resting" represents Shabbos. The light of Shabbos extends three days before (preparation) and three days after (afterglow) — as in the Mechilta's zachor and shamor guarding it from both sides. The three-day journey from Har Sinai and the Ark's going ahead correspond to these spans, and Ezra's enactment of regular Torah reading likewise ensures no three days pass without illumination.