Why only now did Moshe entreat Hashem to be allowed to enter Eretz Yisrael?
(3,23) “And I entreated Hashem at that time, saying. O Hashem, G-d, You have begun to show your servant Your greatness and Your strong hand…Please, let me cross over and see the good land that is on the other side of the Jordan…”
Rashi comments on the words “at that time” - because after I had conquered the land of Sichon and Og, I thought perhaps that the vow that Hashem made that I should not enter the land had been annulled. The Ramban asks on this Rashi, that Sichon and Og were not from the land of Yisrael, so how could he think the vow had been annulled? However, it seems to me that we can explain these words like the way Rashi does, but slightly differently.
But first we will preface with the Midrash on parshas Chukas, which asks why was Aharon held to be guilty in the incident when Moshe struck the rock, as it says in Bamidbar 20:12 “Hashem said to Moshe and to Aharon, because you did not have faith in Me to sanctify Me in the eyes of the children of Yisrael, therefore you will not bring this assembly to the land which I have given to them”. It answers with a parable about a creditor who comes to seize the threshing floor of someone who owes him money, but he takes not only his, but also his neighbour’s. The debtor said to him, “Granted that I am obligated to you, but what did my neighbour do?”. So too said Moshe “Master of the world, I did wrong, but what did Aharon do wrong?”. Therefore, the posuk in Devarim 33:8 praises him “And about Levi he said: Your Tummim and Urim belong to your pious man, whom You tested at Massah and whom You tried at the waters of Merivah”. This Midrash is very puzzling - is Hashem being suspected of acting unjustly?
But the gemora in Shabbos 55a comments on the posuk in Yechezkel 9:4 “Said Hashem, you shall place the letter ת on the foreheads of the men”, that on the foreheads of the wicked you shall mark with blood, and on the foreheads of the righteous with ink, so that the angels of destruction will not harm them. But the attribute of justice argued and asked what the difference was between these two groups. Hashem replied that these are righteous and these are wicked. The attribute of justice continued to argue that the righteous should have reproved the wicked. Hashem replied that it was revealed before Him that they would not have accepted the reproval. The attribute of justice challenged this and said: Before You it is revealed, but who revealed it to them? Hashem agreed to this argument, and furthermore He commanded that the angels of destruction should start with the righteous.
It’s clear from this that the proper, upright approach, going beyond the strict letter of the law, is not to punish the righteous for not reproving the wicked, since they did not actually transgress any sin. Therefore, Hashem, who is All Merciful, argued that this group was righteous, and therefore should not be punished. But according to the strict letter of the law they are liable, and really this is the more essential approach, because had they reproved them they would not have sinned.
Now, it says in the same Midrash quoted above that Yisrael suspected Moshe that the reason why he wanted to hit that specific rock was because he knew the nature of that rock, that it would bring forth water when he hit it. Therefore they argued that he should hit a different rock. Had Moshe had listened to their words it would caused a sanctification of Hashem’s name, but because he got angry with them he erred, and refused to hit a different rock. But Aharon was also present there, and he was not angry, so why did he not admonish Moshe that he should bring forth water from whatever stone that they wanted. And since Aharon did not admonish Moshe, there was a great accusation in the Heavens against him, and not only was he punished, but he was punished first by dying before Moshe, as it says in Yechezkel, that Hashem punished the righteous first. This is the explanation of the parable, that the creditor held that the neighbour was also liable because he had not admonished the debtor to repay his debt. But Moshe who had the trait of uprightness, as did Aharon also, argued that granted he had sinned, but what sin had his brother, Aharon, committed, because this was also the opinion of Hashem who distinguished between the two groups, and said that these are righteous and these are wicked.
Now, it is clear from seforim that according to the traits that a person conducts himself in this world, so does Hashem conduct Himself with him in the upper worlds. If so, if one always goes beyond the letter of the law, and does not insist on acting on the letter of the law, then it is fitting that this is how matters should be conducted with him, and so Aharon was not fitting to be punished for not reproving Moshe. Hashem, however, did not do this, but instead acted according to the strict letter of the law. Therefore, this was a test for Aharon, and he did not complain about Hashem’s conduct. We now understand why the Midrash says that the posuk praises him “And about Levi he said: Your Tummim and Urim belong to your pious man, whom You tested at Massah and whom You tried at the waters of Merivah”. It is saying that even though he is a pious man, and always goes beyond the letter of the law, nevertheless, “You tested him at Massah” when You conducted Yourself with him only according to the strict letter of the law.
It is also clear from the words of Chazal that the death of a Tzaddik atones for the sins of the generation, and the commentaries explain that this specifically refers to a Tzaddik who did not reprove the people of his generation, and thus he is called the cause of their sin, since he did by not reprove them and prevent them from sinning. And so the Tzaddik receives the punishment of the one who transgresses. According to this, since Aharon was punished for not reproving Moshe, it was fitting that Aharon’s death should atone also for Moshe, and Moshe should have been allowed to enter the land.
But in fact Moshe had sinned previously when he had spoken accusingly to Hashem in Shemos 5:22 “Why have you harmed this people”. To this Hashem replied (6:1) “now you will see what I will do to Pharaoh”, and Chazal commented on this posuk that Hashem was saying to him that now you will see, but you will not see what happens to the thirty-one kings. Because of this, Moshe was in doubt as to how to understand Hashem’s decree after the incident with the rock, when He said “therefore you will not bring this assembly to the land”. One possibility was that there had in any case been a decree upon Moshe not to enter the land, but now at the waters of Merivah it was added that also Aharon could not enter, and therefore He said now “you will not bring this assembly”, meaning that now neither of you will enter. The other possibility was that the first sin of Moshe had already been forgiven, as is the opinion of several commentaries, including the Ramban, because Hashem said to him later in parshas Ki Sisoh (Shemos 32:34) “Go, lead the people”. But now at the waters of Merivah it was decreed upon him afresh that he could not enter the land.
Now, if we say that the first decree against Moshe still stood, then it follows that the death of Aharon would not atone for Moshe, since Aharon had not been present when Moshe spoke against Hashem, and so could not have admonished him. But if we say that Moshe had already been forgiven that sin, then the main reason for the decree not to enter the land was for the sin of the waters of Merivah, and Moshe thought that the death of Aharon atoned for this sin, especially together with his prayers, and so he could enter.
Therefore, after Aharon died, Moshe did not pray to entreat Hashem to be allowed to enter Eretz Yisrael, because he thought that the original decree against him still stood. But when he saw the war with Sichon and Og, he reasoned that if the original decree still stood, surely Hashem had told him then that he would not see the war with the thirty-one kings, which also meant that he should also not have seen the war with Sichon and Og, and so it must be the first sin must have been forgiven. Therefore the decree against him now was only because of the sin at the waters of Merivah, and for this it was fitting that the death of Aharon should atone. Therefore he now prayed and said “You have started to show Your servant Your greatness”, with the war against Sichon and Og, therefore “please, let me cross over and see the good land that is on the other side of the Jordan”.