Nombres 14:17

Let my Master’s power be enhanced. By fulfilling Your word.

As You spoke, saying: What is the statement?

And now, I beseech Thee, magnify Thy power, O Lord, and let mercies be fulfilled upon us, and appoint me for (this) great people, as Thou hast spoken, saying:

AND NOW, I PRAY THEE, LET THE POWER OF THE ETERNAL BE GREAT, ACCORDING AS THOU HAST SPOKEN, SAYING. “And what is that utterance? The Eternal is long-suffering — both to the righteous and to the wicked. When Moses ascended to heaven [to receive the Torah], he found the Holy One, blessed be He, writing: The Eternal is long-suffering. Whereupon he [Moses] said to Him: ‘To the righteous.’ But G-d answered him, ‘Also to the wicked!’ Moses then said, ‘The wicked — let them perish!’ Whereupon G-d said to him: ‘By your life! You will [eventually] need to resort to this’ [attribute — that G-d is long-suffering even with sinners]. When the Israelites had sinned because of the golden calf and spies, and Moses prayed to G-d that He be long-suffering with them, the Holy One, blessed be He, said to him, ‘Did you not tell Me that this is [only] for the righteous!’ Whereupon Moses answered Him, ‘But did You not tell me that it is also for the wicked. Let then the power of the Eternal be great to do as You have spoken.’” These are the words of Rashi, based on the interpretation of Agadah.
The way of Truth you will recognize because G-d’s Name in this context is written with Aleph Daleth (A-donoy) — [a Name which alludes to the attribute of judgment], and Moses meant to say that the greatness be in the power which is mercy, since it was the attribute of judgment that was directed against them.
Now Moses mentioned among the [Divine] attributes long-suffering, and plenteous in loving kindness, but he did not mention “truth” [although it is also one of the Thirteen Attributes], for according to the attribute of truth they would have been guilty. Nor did Moses mention keeping mercy unto the thousandth generation,, Verse 7. because Moses did not pray [for mercy] here on the basis of the merit of the patriarchs, and [therefore] he did not mention Abraham, Isaac, and Jacob at all in this prayer. The reason [for not mentioning them] was because the Land was given to the patriarchs, and it is from them that they were to inherit it, but they rebelled against their ancestors, and did not want the gift which the patriarchs desired very much, so how could he say now, [Remember Abraham, Isaac, and Israel, Thy servants,] to whom Thou didst swear by Thine own self, … and all this Land that I have spoken of will I give to your seed,, 32:13. since they were saying: “We do not want this gift!”
Moses …

יגדל נא כח, to restrain Your anger. We know from Solomon in Proverbs 16,32 that “it is better to practice restraining one’s anger, than to display brute force as a proof of one’s power. Ruling one’s spirit is better than conquering a city.”

'יגדל נא כח ה, to suppress the demands of the attribute of Justice.

'ועתה יגדל נא כח ה, “and now I pray let the Power of the Lord be great;” Moses considers a display of being able to suppress one’s anger as the greatest proof of greatness. Our sages in Ethics 4,1, have defined the term גבור, “hero,” as someone who can conquer his emotions when they threaten to overrule his intellect. This is what Solomon already taught us in Proverbs, 16,32: טוב ארך אפים מגבור, “he who is slow to anger is better than the mighty.”

כאשר דברת לאמר, “as You have declared, saying:” Moses refers to Exodus 33,13: where he had spoken to G–d asking Him to reveal to Him His way of reacting to the people’s sins if and when they would occur. He had requested that G–d reveal to him all of His attributes relevant to judging His creatures. At that time, when the glory of Hashem, passed by him while he was hiding in the cleft of a rock, one of the attributes G–d had revealed to him was the one known as ארך אפים, “slow to anger.” At this point Moses did not remind G–d of His attribute רחמים, “the Merciful One;” on that occasion both of theses attributes had to be called upon, whereas here there was no pointing referring to any attribute other than that of Mercy. He also did not refer to the attribute אל, G–d in His capacity of judge, seeing that he could not hope that G–d would completely ignore the people’s lack of faith and their having accused Him of hating them. He could only ask G–d to temper His anger by limiting the penalty. Moses concentrated on those attributes which, if displayed by G–d at this time, would preserve the people’s future, even if the people personally guilty of accepting the slander of the ten spies would obviously have to pay a price, i.e. they had rejected the Holy Land, therefore G–d would accept their rejection of it and not make them live in it.

Our author details why Moses refrained from mentioning any Divine attribute which would prove counterproductive if Moses would refer to it.