פירוש על בראשית 49:24

ותשב באיתן קשתו means his power (i.e. his rule as viceroy) was strongly (באיתן) established.

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,²²⁹Zechariah 4:7. [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.