Moshe beholds the angel of Hashem within the burning bush and he comes closer to see why the bush is not consumed. Then Hashem calls to Moshe and speaks to him for the first time:
And He said, “Do not approach here; slip off your shoes (NA’ALECHA) from upon your feet, because the place upon which you stand is holy ground (ADMAT KODESH HU)” (Shemot 3:5).

What is the significance of removing the shoes?
Perhaps shoes insulate man from the dust that is both his origin and his final destination. Forgetting one’s mortality results in pride. Accordingly, Moshe must humble himself in the presence of Hashem.

Some commentaries explain that Moshe’s journey towards holiness is yet to begin. Ibn Ezra says Moshe must remain in his place and not come near the bush at all. Sforno (R. Ovadia ben Yaakov Sforno, c. 1470-c.1550), on the other hand, reads: slip off your shoes — even in the place where you are; not only is the place of the bush holy, but even the place upon which you stand is holy ground.

Ramban agrees with Ibn Ezra, that Moshe has not yet attained the highest degree of prophecy. That would happen at the Revelation at Mount Sinai: He (Moshe) drew near to the thick darkness where G-d was (Shemot 20:18).

The reason for removing the shoes is because the entire area had become sanctified by the Divine Presence, and no barrier should be placed between Moshe and the holy ground. In this connection Ramban quotes the Midrash (Shemot Rabbah 2:13):
“Any place where the Divine Presence is revealed, wearing shoes is forbidden. So regarding Yehoshua, “Slip off your shoe.” And similarly the Kohanim minister in the Sanctuary only while barefoot.”

The reference to Yehoshua is the angelic visitation in Yericho:
And the captain of Hashem’s host said to Yehoshua,
“Slip off your shoe (NA’ALCHA) from upon your foot,
because the place on which you stand is holy
(KODESH HU)”. And Yehoshua did so (Yehoshua 5:15).
In the Sanctuary, the feet of the Kohanim must touch the floor without interposition, because the floor itself sanctifies; otherwise, the sacrifice is invalid (Zevachim 15b, 24a). Even nowadays when the Kohanim bless the congregation in the synagogue they remove their shoes (see Sotah 40a and Orach Chayim 128:5).

Rav Avraham Yitzchak HaKohen Kook (1865-1935) argues that sometimes removing shoes is itself a significant or even obligatory act. Thus, before the priestly blessing or before Yom Kippur, the right shoe should be removed first (Otzerot HaRaayah III pp. 229-230). A similar observation can be made regarding Moshe and Yehoshua: the removal of shoes is a significant step in being elevated in holiness.

Some commentaries see in the removal of shoes symbolic and mystical meaning. Daniel (7:15) speaks of the body as a sheath for the soul. Nefesh HaChayim (R. Chayim of Volozhin, 1749-1821) says that the relation of the body to the soul is comparable to that of the shoe to the body. Not only is a shoe an outer covering, but it covers the nethermost part of the body; similarly, the body houses only the lowest part of the soul, while the root of the soul exists in the upper worlds. Involvement in bodily matters is an impediment to spiritual achievement. In order to achieve holiness, one must be wholly devoted to Heaven (Gate I ch. 5; Likutei Maamarim 14). In a similar vein see also Haamek Davar (R. Naftali Tzvi Yehudah Berlin, 1817- 1893); Peh Kadosh (R. Yitzchak [“Reb Itzele”] ben Chayim Volozhiner, 1780-1849); and Malbim (R. Meir Leib ben Yechiel Michael, 1809-1877). A full treatment of this approach is found in the SHeLaH (Shenei Luchot HaBrit, R. Yeshayah ben Avraham HaLevi, c. 1565-1630) on our verse. Man, so to speak, wears two “skins”— the animal skins he wears as shoes, and his own skin:
With skin and flesh You have clothed me (Iyov 10:11).

The physical body was fashioned by Hashem Himself from the dust of the earth, and so should be ADMAT KODESH; however, because of man’s sin it becomes base matter.

SHeLaH notes here three differences between Moshe and Yehoshua: Moshe is told to remove his shoes (NA’ALECHA), whereas Yehoshua is commanded to remove his shoe (NA’ALCHA); In the case of Moshe the ground is holy (ADMAT KODESH HU), but with Yehoshua the word ADMAT is not used (KODESH HU); After the command it says, And Yehoshua did so, but there is no such statement with Moshe.

Moshe was prepared to attain holiness from the moment of his birth: “And she saw him that he was good (Shemot 2:2) – The entire house was filled with light (Sotah 12a).”

Ultimately Moshe reached such an exalted level of prophecy that even his body was purified: The skin of his face shone (Shemot 34:29). Consequently, Moshe received prophecy without trembling or lapsing into a trance. Yehoshua, on the other hand, did not rise to Moshe’s level.

Thus, the place where Yehoshua stood is holy, while Moshe sanctifies the entire ground as the holy of holies. Since Moshe will attain the highest level of sanctity, Hashem instructs him to remove his shoes, meaning both to take off his actual shoes and divest himself of his body and purify it.

Yehoshua was ordered merely to take off his shoe, And Yehoshua did so. However, Moshe was commanded to dissociate himself from the corporeal, which is not a physical act, and thus it is unfitting to say that he “did so.” Moreover, even though he began this purification at the burning bush, the process was not complete until the Revelation, so it would be premature to say he “did so” now.

We conclude with the holy SheLaH’s words: “It is proper for a person to  learn from this that one who is in a holy place needs to sanctify himself very well. And if he reaches a level of greater holiness he needs to sanctify himself more and more.”