Rabbi Shalom Sharabi points out that this second explanation does not resolve the grammatical irregularity.

Perform the Mitzvah of Torah study completely, learning both the Written and Oral Torah….

A [third] possibility is that the Torah is here discussing [the specific Mitzvah of] Torah study. We note that [Moses] began this passage addressing us in the singular [and continues in the next verse] saying, "Remember the journey [on which G‑d guided you these forty years in the desert]…how He afflicted you [and made you hungry and fed you the manna]…." (Deut. 8:2-3) It therefore appears to me that this passage is talking about Torah study, for it, too, is called "the Mitzvah". The word "all" then comes to include the Oral Torah, which is also called "the Mitzvah".

"Perform all the Mitzvahs that I command you" thus means: "perform the Mitzvah of Torah study completely, learning both the Written and Oral Torah".

Proof of this may be seen in the words: "Take care to do". Our sages taught that in the verse, "You shall be careful and do them"; (Deut. 7:12) "you shall be careful" refers to learning [how to do the Mitzvahs] and "and do them" refers to performing [them,] as it sounds. (Sifrei, parashat Re'eh 58, 59) Here, too, "Take care" means be sure not to forget what you have learned, so that you can do it, as indicated by "to do…".

It never happened that one individual was responsible for knowing the whole Torah other than in the cases of Moses and Joshua….

This explains what I learned about the [following] passage of the Mishna: "Moses received the Torah from Sinai [and transmitted it to Joshua, and Joshua to the elders, and the elders to the prophets, and the prophets transmitted it to the Men of the Great Assembly]." (Avot 1:1) It was pointed out that with regard to Moses, the expression "received" is used, whereas with regard Joshua, the expression "transmitted to" is used. It would seem that it would have been more consistent either to speak of both of them as having "received" or as having been "transmitted to". Furthermore, the next two stages, the elders and the prophets, are not spoken of as having received or having been transmitted to. Finally, the prophets are said to have "transmitted" it to the Men of the Great Assembly. Why not follow the precedent and simply say, "…and the prophets to the Men of the Great Assembly?"

It was answered that "transmitted to" implies being acted upon forcefully, as it is written, "and [the conscripts] were handed over from amongst the thousands of Israel" (Num. 31:5) in connection with [the conscription for] the war against Midian.

The word for "were handed over" (in Hebrew, "yimasru") is the same verb used in the Mishna for "transmitted" ("masra" and "masru").

The Jews had to be conscripted by force [to fight the war against Midian] since they knew that Moses would die thereafter (Rashi ad. Loc.), as it is written, "Avenge the vengeance [of the Israelites against Midian] and then be gathered [unto your people]." (Num. 31:2)

Thus, the verb in question denotes involuntary transmission.

Therefore, inasmuch as our holy Torah "is longer than the earth [and wider than the sea]" (Job 11:9), Moses had to transmit it to Joshua forcefully, for Joshua was unable to receive it all on his own. Only Moses had the power to receive it easily. But Joshua received it only on Moses' power, beyond his ability.

As for "and Joshua to the elders": Since he was transmitting it to many people, his own power was not required, for amongst many people, one will remember most of what he learned, another most of what he learned, [and thus they will all, together, cover the subject]. It is therefore not as difficult as it is with an individual who has to remember the whole Torah by himself.

The same pertains for "and the elders to the prophets", a transmission from the many to the many.

But as the generations wore on, human intellect diminished, until even transmission from the many to the many required strength. It is therefore stated that "the prophets 'transmitted it' to the Men of the Great Assembly".

Thus, it never happened that one individual [was responsible for] knowing the whole Torah other than in the cases of Moses and Joshua.

Therefore, [here,] Moses says "the whole Mitzvah" - meaning the whole Torah - "that I command you" - in the singular, as if to say "I am teaching it to each of you individually, just as to Joshua. But I know that you will not all be able to remember it all; therefore I tell you" - in the plural - "to at least take care of it amongst all of you, so that each one remember at least part of it." He then reverted again to the singular, saying, "Remember the journey…."

In other words, the whole passage is addressed to each individual Jew, in the singular, except for the clause "Take care [implied you, pl.] to do, in order that you [pl.] live and you [pl.] multiply, and you [pl.] come and you [pl.] inherit the land that G‑d swore to your [pl.] fathers." The next verse continues, "Remember [implied you, sing.] the journey on which G‑d guided you [sing.]…" and the rest of the passage is in the singular. The plural clause is addressed to the people as a whole who are collectively responsible for remembering amongst all of them the whole Torah.

Similarly, [we can better understand this passage with the help of] something written by the pious Rabbi Yonah [of Gerondi] (Shaarei Teshuva 3:30) regarding the sequence of verses [in another Biblical passage]. King Solomon said, "Honor G‑d with your wealth…and He will fill your storehouses [with satiation]…. Do not despise, my child, G‑d's discipline…[for G‑d chastises whom He loves]." (Proverbs 3:10-12) He wrote that [this implies that] even if G‑d does not "fill your storehouses", do not say that it is pointless to serve Him, "for G‑d chastises whom He loves."

If it doesn't happen, don't rebel, for it might be a test….

So, too, did [Moses] say here. "Even though I told you 'you shall take care to do…in order that you live [and multiply]’, if it doesn't happen, don't rebel for it might be a test, 'for G‑d is testing you to know‘ [paraphrase of Deut. 13:4] 'if you will keep His Mitzvahs or not.' So too, [do not rebel even] if pain or suffering befall you [for He is testing you] like the way He tested you by making you wander for forty years in the desert, to see if you would rebel and say that 'look, we are keeping His Mitzvahs and learning His Torah, and He has been tiring us out on this journey for forty years, and has not brought us into the land of Israel.'"

[Moses] began [this section of this passage] in the plural but then switched to the singular. This is because, generally, whoever keeps the Mitzvahs will prosper and live. Thus, he said: "Take care [in the plural] to do, in order that you [in the plural] live…", for this is the general rule. If there is an exception or two, that is, "a righteous person who suffers" (Berachot 7a), it is only a test. He therefore continued, "Remember [implied you, in the singular] the journey on which G‑d guided you [singular]…how He afflicted you [singular] and made you [singular] hungry…." Meaning, "from this you should understand that if you are a righteous person who suffers, this might be an affliction that He, may He be blessed, is inflicting on you in order to cleanse [you] of [the existential filth you have accrued from] some sin. For G‑d chastises whom He loves."

chanoch adds: Kabbalah teaches that people are tested in order to provide you additional Light to reveal. It is also true that no tests is given in which you are the cause of the test not HaShem. Also there is no test for you that is impossible for you to pass.

The Arizal now explains why the manna is mentioned in this context. We have explained the passage to be describing how G‑d sometimes inflicts suffering on the righteous. Wasn't the manna a good thing?

Even though the manna was a spiritual and important form of nourishment, they still suffered and were hungry, as it is written, "…and our souls are fed up with this light bread" (Num. 21:5), and "our eyes see nothing but manna" (Ibid. 11:6).

These verses indicate that the Jews did not appreciate the manna, as the Arizal will now explain.

G‑d's intention was to teach them that not everything that seems good is really good….

Scripture here repeats this complaint on their behalf and justifies it, as it is written: "[and fed you the manna,] which you did not know and your fathers did not know." It is normal for people to prefer food they are used to, and if they are brought a better type of food, they do not appreciate it, since they are not used to it. The same is true here, especially since [the manna] was a spiritual food, and physical beings desire only physical food.

chanoch adds: Manna is a spiritual food that the midrash explains took mupon itself the consciousnes of the eater. If they wanted a cheeseburger it tasted like a cheeseburger. To do this consciousness change on the manna required a spiritul level that not all people had achieved.

G‑d's intention [in nonetheless feeding them manna] was to teach them that not everything that seems good is really good. For suffering serves to cleanse sin, and it is therefore better [than apparent good]. This is why we are taught to bless G‑d [even] for misfortune, just as we bless Him for good fortune. (Berachot 54a) And so did Nachum of Gamzu say, "This [misfortune] too, is for the good" (Taanit 21a), even though it appears evil to everyone.

This is the meaning of the phrase, "in order to teach you that man does not leave by bread alone…" - which you consider good - "…but rather by every word that issues from G‑d's mouth" - i.e. everything G‑d decrees, whether [it appear] good or bad; on this - "shall man live" better. Therefore, "Do not despise, my child, G‑d's discipline."

Translated and adapted by Moshe-Yaakov Wisnefsky from Sefer HaLikutim and Likutei Torah parashat Ekev; subsequently published in "Apples From the Orchard."