Genèse 49:24

But he returned to abide in his early strength, and would not yield himself unto sin, and subdued his inclinations by the strong discipline he had received from Jakob, and thence became worthy of being a ruler, and of being joined in the engraving of the names upon the stones of Israel.

BY THE HANDS OF THE MIGHTY ONE OF JACOB. This befell him from the Holy One, blessed be He, Who is the Mighty One of Jacob. And from there [from his position as viceroy], he became worthy to be the feeder of the foundation stone of Israel, that is, the source of the tribes of Israel. The word “even” (stone) has the same meaning here as the word “even” in the expression, the chief stone, [where it means high position]. This is the language of Rashi. “From the G-d of thy father did this befall you, and He will help you. [And with the Almighty, i.e.,] and your heart was with the Holy One, blessed be He, when you did not hearken to the words of your mistress, and He will bless you.” This is also the language of Rashi.
Rabbi Abraham ibn Ezra said that the letter mem in the expression, mei’e-il avicha (‘from’ the G-d of thy father), is also to apply to the expression, ve’eith Sha-dai, [as if it read, umei’eith Sha-dai (and ‘from’ the Almighty)], and He will bless thee.…

ותשב באיתן קשתו, there is a certain heavy and strong bow called arbalatra which is seated on a strong wooden frame called purka, and which, if the archer pulls with all his might bringing his arms all the way back to his body, enables him to shoot the arrow over a longer distance. A weak individual cannot operate such a bow. We have to understand the verse as describing a scenario describing Egyptians shooting their arrows of hate at Joseph until he was imprisoned, bound hand and foot. Nonetheless, the same Joseph afterwards emerged and became king over his former tormentors. This was because his קשת, bow, was stronger than that of his adversaries. He proceeded to imprison his enemies, as we know from Psalms 105,22 לאסור שריו בנפשו “to imprison (discipline) those who had previously demonstrated their hostility against him.

ויפוזו זרועי ידיו, he contracted his arms quickly remaining steadfast when he pulled the string of the bow and flung his arrows against them seeing that he was a powerfully built man, able to pull the bow all the way back. We do find the word זרוע used in connection with archery in Psalms 18,35 ונחתה קשת-נחושה זרועותי, “my arms can bend a bow of bronze.” The wording describes the tensing of a bow. A similar expression occurs in Psalms 38,3 כי חציך נחתו בי ותנחת עלי ידך, “for Your arrows have struck me; Your blows have fallen upon me.” [the reference is to G’d’s “arrows.” Ed.]

ויפוזו, leaping in a wild dance, as in Samuel II 6,16. Here the expression is applied to Joseph’s hand, arms. In Samuel the word כרכר describes parallel motions with the legs. The image conveyed by the word is that of twirling one’s limbs.

מידי אביר יעקב, Joseph’s victory was due to the assistance of G’d, the One Who proved Himself as the Mighty one to Yaakov, Who grants dominion to kings and princes. The expression אביר יעקב is a duplicate of what follows i.e. רועה אבן ישראל. We find the expression אביר also in connection with King Sha-ul in Samuel I 21,8 i.e. “Doeg the Edomite, Shaul’s chief herdsman, אביר הרועים. The reason why the shepherds are called אבירים is because their cattle, the oxen, are called אבירים both in Psalms 68,31 and 22,13....

מידי אביר יעקב, Yaakov is reminding Joseph of who it was that is responsible for his exalted position in the world, none other than the רועה אבן ישראל, the Shepherd Who has provided generously for the entire family of Israel.

ותשב באיתן קשתו. The reply to such accusations was given by Pharaoh himself when he challenged his servants with the words: “where else can we find such an individual endowed with the spirit of G’d?” (41,39) As a result, Joseph did not have to use his own ammunition. In other words, he could keep his arrows in his quiver, unused.

ויפוזו זרעי ידיו, his arms were immeasurably strengthened when Pharaoh transferred his ring with the Royal seal to him.

מידי אביר יעקב, however, the real salvation emanated from the G’d Who had proven Himself by doing the same for Yaakov. It is He Who enables Yaakov’s descendants to survive among the hostile nations, so that in the end only they will survive. The very name “Yaakov” suggests that in the end there will be only he. In the meantime, He is the One Who kept you alive and saved you from the slanderers who took aim at you.

משם, from then on the

רועה אבן ישראל, He will continue to act as the Shepherd of Israel preserving His people who will endure like אבן, a stone. It does not matter whether this stone is intrinsically precious or not, being a “stone” it will endure. The enduring nature of a stone is best illustrated in Daniel 2,34: “As you watched, a stone was hewn forth without hands and struck the image on its feet of iron and earthenware and crumbled them.” [Daniel telling the king who had forgotten his dream which he had dreamt. The stone in the dream represented Israel, the image, the nations of the world. Ed.] The reason Israel would survive is because they keep their faith with G’d and man. Sanhedrin 104 explains that the reason why Jews, even when defeated, exiled, etc.’ rose to high positions in their host country was because the rulers valued their loyalty.

ותשב באיתן קשתו, the bow from which they aimed their arrows at him broke, whereas the supposed victim, Joseph, remained unhurt, not only that, but advanced to ever higher positions.

ויפוזו זרעי ידיו, his hands and arms kept getting stronger, i.e. he acquired the means to punish those who had slandered him. We encounter the expression מפזז in Samuel II 6,16 as a description of strength. It appears there next to the word מכרכר, a variation of the root פזז having a similar meaning, when applied to the legs. What was the source of Joseph’s strength?

מידי אביר יעקב, the G’d Who had manifested Himself many times as the Power that stood by his father and lent him strength, not allowing him to collapse in spite of all the troubles that had dogged him for many years.

משם רועה אבן ישראל, Joseph’s great honour originated from there, משם, from the Shepherd of Israel. Seeing that a stone represents something solid, unshakable, permanent, all of Israel is compared to a stone, אבן. Alternately, seeing that Yaakov/Israel was the founding father of the nation, Yaakov refers to himself in that manner, i.e. the corner stone of the nation. Rabbeinu Saadyah gaon translates it into Arabic as עצם, the essence. This conforms to what we said.