Approaching the monumental event of receiving the Torah, the Israelites had to undergo a profound process of preparation and purification. The Torah did not originate from within the nation; rather, it was given to them from an external, divine source. Because of the vast gap between their human condition and the spiritual level required to stand before God, purification processes were necessary to bridge this divide. These steps symbolized a rebirth for the nation and impressed upon their hearts the sheer weight of the moment [רש״ר הירש]. By instructing Moses to go to the people, God effectively agreed to the Israelites' request to hear the Commandments face-to-face. However, He made it clear that such direct revelation, without Moses acting as a full mediator, demanded rigorous preparation [העמק דבר, מלבי״ם].
The central requirement was for the people to be sanctified. A primary approach among some commentators is that this simply meant a practical summoning and preparation for what was to come [רש״י, רשב״ם, שטיינזלץ]. However, most commentators agree that this holiness required a complete withdrawal from impurity, specifically avoiding marital relations and washing the body in water [רמב״ן, אבן עזרא, שד״ל]. Beyond physical purity, this directive also demanded a spiritual elevation above worldly desires and baser instincts. During those days of preparation, Moses sought to recount the history of the world and the Commandments to the people, educating and uplifting their souls, because true holiness is internal and rooted in the refinement of character and mindset [הכתב והקבלה, מלבי״ם].
The allotted time for this process was a span of two days, providing adequate time to achieve this state of purity [בכור שור]. Recognizing the high spiritual degree of the Israelites and the need for absolute biological purity, Moses deduced that an additional, third day of preparation was necessary and implemented it on his own initiative [תורה תמימה, חתם סופר]. On a conceptual level, the requirement to sanctify themselves for the present day and the following day suggests that holiness was never meant to be confined to the singular moment at Mount Sinai. Instead, it must continue to illuminate their future, extending into the mundane routines and business of everyday life [פרדס יוסף].
An additional step in this preparation was the washing of their garments. On a basic level, just as it is improper to stand before a human king in soiled clothing, it is certainly unacceptable to do so before the King of Kings. The cleanliness of their garments served as an outward symbol of the inner purity of their souls [שד״ל, קאסוטו]. Practically, one might wonder where an entire nation found enough water in the desert to wash and immerse themselves; some suggest this was made possible by the miraculous well of Miriam [ברכת אשר]. According to Jewish law, commentators agree that the instruction to wash clothing inherently carries the obligation to immerse the entire body in a ritual bath [רבנו בחיי, תורה תמימה, תולדות יצחק].
On a symbolic level, the body itself is viewed as the garment of the soul. Clothing represents human thought, speech, and action—the tools through which the soul expresses itself in the world. While Moses was given the role of sanctifying the nation, the physical act of washing garments was placed upon the people themselves. This teaches a vital lesson: even when a great leader inspires the nation and connects them to God, the responsibility to cleanse one's own character and actions from negativity ultimately rests on each individual [מלבי״ם, חומש קה״ת].