Deuteronomy 10:1

At that time did the Lord say to me: Hew thee two tables of marble according to the form of the first; and ascend before Me into the mountain, and make thee an ark of wood.

At that time during the abovementioned [9: 25] forty days.

a wooden ark The Exegetes, of blessed memory, have said [Palestinian Talmud Soṭa 8: 3 (22b)] that Moshe himself made an original ark, different from the one that was later made. Their evidence is I made an ark, followed by I hewed…, after which Moshe says “I put the tablets into the ark which I had made” — and their understanding is greater than ours. But it would seem that “The glory of God dwelt” [Exodus 24: 16] refers to the glory that the elders had already seen [Exodus 24: 10]. The exact date of Moshe’s first ascent is not clear, and a surface reading of Scripture suggests that Moshe only fasted for eighty days: The period denoted by “I stayed on the mount, as the first days:” [: 10] coincides with the second forty-day period [9: 25], so that the sense of the passage is, When I had stayed in the mountain these forty days, God “hearkened” unto me [cf.: 10], and said, “lead the march” [: 11] — which is the same as “go, lead the people” [Exodus 32: 34]. If all this be true, then the “wooden ark” [: 1] was made at Moshe’s command , but it is actually the same ark that B ә ṣal כ el made [cf. Exodus 37: 1].

AT THAT TIME THE ETERNAL SAID UNTO ME: ‘HEW THEE TWO TABLETS OF STONE.’ After I cast myself down in prayer before G-d for forty days and forty nights, He was reconciled with me that He would write the second Tablets. However, the first ones were the work of G-d, and the writing was the writing of G-d, whereas these [second Tablets] He commanded me that they be hewn by my hands and the writing will be like the writing on the first ones, by the finger of G-d., 31:18.

בעת ההיא אמר ה' אלי "פסל לך", in spite of all my prayers, the repair, the reconstitution of what had been damaged, proved to be incomplete,for the substitution for the first set of Tablets was not something made by G’d Himself, and this is why He commanded me: פסל לך, “carve it out by yourself!”

בעת ההיא, “at that time;” after G–d had pardoned the people’s sin and instructed him to hew new Tablets out of material found on earth. He did so to make sure the people could not accuse Moses at a later stage to have smashed the Tablets G–d had given him for the people. After all, they had been the most precious gift the people had ever been meant to receive. This is also what Kohelet had in mind when he said in Kohelet 3,1: there is a time for everything, a time for every imaginable “thing.” There was a time when the Tablets had to be smashed, and there was another time when new Tablets had to be made. Moses refers to the second such time. A different interpretation of the words: פסל לך ההיא. The word: פסל, which is part of the word פסולת, rubbish, chips, is what will be Moses’ after he had hewn out the new tablets from stone. It would be his reward for performing that work. It would enrich Moses as the “stone” from which he hewed these tablets were sapphires. There is a disagreement between the sages about where Moses had been able to find those sapphires. According to Rabbi Levi, Moses found this under the throne of G–d; according to the opinion of Rabbi Chanan, he found it beneath his tent. The source of this discussion is found in Song of Songs 5,14: ידיו גלילי זהב, “his arms are rods of gold, are studded with sapphires overlaid with ivory.” i.e. the tablets, i.e. the commandments were arranged five on each tablet. (Compare Talmud tractate Shekalim chapter 6, halachah 1) Yet another interpretation of the words: פסל לך: I appoint you as king and you may disqualify anyone and anything that you desire. (Tanchuma section 9 on our portion)

ועלה אלי ההרה, “and ascend the Mountain to Me;” ועשית לך ארון עץ, “and make for yourself a wooden ark” (after ascending). According to Tanchuma, Moses did not make this ark afterwards but before ascending [as where was he to put the Tablets in the interval after returning from the Mountain? Ed.].