This event recalls a similar event which began the Exodus:
And He said, "Do not come closer. Remove your sandals from your feet, for the place on which you stand is holy ground. (Exodus 3:5 JPS 1999)
The captain of the LORD's host answered Joshua, "Remove your sandals from your feet, for the place where you stand is holy." And Joshua did so. (Joshua 5:15 JPS 1999)
In the commentary of Joshua, Carol Meyers states:
"Remove...holy" quotes Exod. 3.5 directly and provides one more connection between Joshua and Moses. 1
Actually, chapter 5 of Joshua contains four parallels with Moses bringing the people to the Promised Land:
- Removal of sandal(s)
Joshua’s encounter with the captain of the LORD’s host follows the circumcising those who were born in the wilderness (5:2-8), observing the Passover (5:10-11), and the end to the manna (5:12). This same sequence occurs in Exodus. After the burning bush, Moses encounters the LORD who seeks to kill him but is saved when Zipporah circumcises their two sons (born in the wilderness). In Egypt the LORD institutes the Passover and the manna begins falls after crossing the Red Sea.
The sequence of events in Exodus is same except for the command in the question:
A: Moses: Remove your sandals (Sinai)
B: Moses: Circumcision of Moses sons born in the wilderness
C: Moses & Joshua: Passover in Egypt
D: Moses & Joshua: Manna starts
B’: Joshua: Circumcision
C’: Joshua: Passover
D’: Joshua: Manna stops
A’: Joshua: Remove your sandal (near Jericho)
"Removing" is one of the first events for Moses, while it comes at the end of the sequence for Joshua. Alternatively, the command to Joshua can be seen as starting a new sequence, the campaign to take possession of the land. Given these similarities it is reasonable to conclude the two instructions are intended to be considered in light of the other.
Footwear and Location
As Abu Munir Ibn Ibrahim discusses in his answer to this question, the text need not be understood as removing a single sandal; it can be seen as a collective singular such as footwear. However, while the textual variances can be resolved by an understanding the two phrases mean the same, that approach has the effect of concealing the fact there are differences:
Exodus: שַׁל־נְעָלֶיךָ מֵעַל רַגְלֶיךָ כִּי הַמָּקֹום אֲשֶׁר אַתָּה עֹומֵד עָלָיו אַדְמַת־קֹדֶשׁ הֽוּא
Joshua: שַׁל־נַֽעַלְךָ מֵעַל רַגְלֶךָ כִּי הַמָּקֹום אֲשֶׁר אַתָּה עֹמֵד עָלָיו קֹדֶשׁ
Attempting to reconcile the two to give them the same meaning discounts the real differences which are present. There may be a question of footwear (sandals/sandal). There is the use of עוֹמֵ֣ד ("on which") in Exodus and עֹמֵ֥ד ("where") in Joshua, and "ground" is used in Exodus not in Joshua.
The LXX offers some insight:
Exodus: …λῦσαι τὸ ὑπόδημα ἐκ τῶν ποδῶν σου ὁ γὰρ τόπος ἐν ᾧ σὺ ἕστηκας γῆ ἁγία ἐστίν
Joshua: …λῦσαι τὸ ὑπόδημα ἐκ τῶν ποδῶν σου ὁ γὰρ τόπος ἐφ᾽ ᾧ σὺ ἕστηκας ἅγιός ἐστιν
Exodus: Loose the sandal from your from your feet! For the place on which you are standing is holy ground. [LXX-NETS]
Joshua: Loosen the sandal from your feet for the place where you stand is holy. [LXX-NETS]
In both the collective singular is present (“feet”) but with a singular piece (“sandal”). The NET translator for Exodus renders λῦσαι “loose” where the translator for Joshua renders the same word as “loosen.” Apparently one recognizes the potential ambiguity of a command which applies to a single sandal. Based on the LXX, the footwear and the command given to Moses and Joshua are identical and apply to a single sandal. In other words, both Moses and Joshua are given identical instructions. What varies between the two is why the need to remove the sandal.
The omission of אַדְמַת ("ground") in Joshua is also reflected in the JPS translation:
Exodus: for the place on which you stand is holy ground
Joshua: for the place where you stand is holy
Using the LXX, Moses was standing in holy ground and Joshua was standing where it was holy. The difference could reflect Joshua was standing on the "Promised Land" while was on Mount Sinai. Using the JPS, the place on which Moses was standing (Mount Sinai) was holy ground and for Joshua the place which he was standing (Israel) was holy.
The difference could also be understood by the Ark of the Covenant which had been carried across the Jordan into the land where Joshua was standing. The Holy Place and Most Holy Place were identified by the Ark. So the omission of "ground" in Joshua could be taken as a reflection the presence of the Ark in Israel made the place (collective) “where” Joshua was standing holy while Moses was standing on the mountain, a place (singular) with holy ground.
A type of "collective singular" which can be applied to reconcile the two commands is found in why there is a need to remove the sandal. Moses is on holy ground (singular); Joshua is on the place (Israel) which is holy.
Based on the Hebrew collective singular and the LXX, the command given to Moses is the same as that given to Joshua: loose a single item from your feet. There is no plural/singular difference. Both Moses and Joshua were instructed to remove the same number of pieces from the feet. Logically this should be applied to both feet (although nowhere does the text state how Moses or Joshua responded to the command). If there is a difference in the type of footwear, the practical consequence is insignificant. If a single piece of footwear is to be “loosed” it is that act which matters, regardless of the exact nature of what is worn. The fundamental difference is where the meeting takes place as the text shows.
If the LXX is correct in seeing the command as the removal of a single sandal, there are similar events in Deuteronomy (25:9) and Ruth (4:7, 8) both of which are in the context of the kinsman-redeemer. The instruction to Joshua was given after Deuteronomy and the removal of a single sandal now has legal implications.
Joshua's location is "by Jericho." He was less than 20 miles from Bethlehem where Boaz will remove his sandal as described in Ruth:
Then Boaz said, “The day you buy the field from the hand of Naomi, you also acquire Ruth the Moabite, the widow of the dead, in order to perpetuate the name of the dead in his inheritance.” Then the redeemer said, “I cannot redeem it for myself, lest I impair my own inheritance. Take my right of redemption yourself, for I cannot redeem it.” Now this was the custom in former times in Israel concerning redeeming and exchanging: to confirm a transaction, the one drew off his sandal and gave it to the other, and this was the manner of attesting in Israel.
(Ruth 5-7 ESV)
The event, especially in the case of Joshua (who is about to take possession of the land), is in effect where and how the custom of redeeming and exchanging in Israel has its legal basis. It is "a custom" which began with the command given to Joshua. If the meaning is to remove a single sandal, the instruction should be considered in the light of the legal significance of that action.
1. The Jewish Study Bible, Oxford University Press, 2004, p. 473