The JPS Torah Commentary on Genesis
Edited by Nahum Sarna & Chaim Potok 

Excerpt of comments on Genesis 49:22

Joseph is a wild ass,
A wild ass by a spring
--Wild colts on a hilside.

	"Joseph",  the blessing of Moses similarly uses the name
"Joseph" for the two tribes of Ephraim and manasseh; but such
usage is rare.  Otherwise, teh name designates the entire
northern kingdom of Israel.  The two tribes are know as "the
House of Joseph" or "the sons of Joseph".

	"a wild ass...A wild ass",  literally, "a wild ass is
Joseph, A wild ass by a spring"--an example of anaphora (see
Comment to v. 2 [This is what the comment on v. 2 says: The
repetition of the same word at the beginning of both parallel
clauses, a phenomenon known as anaphora, is a characteristic of
Hebrew poetry.]).

	"wild ass",  Hebrew "ben porat" is probably a word play on
"Ephraim", the more important of the two Joseph tribes, for a
member of the tribe was designated " 'efrati ( 'prti)".
	The present translation takes "ben" as signifying a class or
quality and "porat" as a feminine poetic form of "pere' ".  The
parallel clause "banot tsa`adah" is understood as the Hebrew
equivilent of Arabic "banat sa`adat", "wild colts".  This
rendering has the of maintaining the pattern of the figurative
use of animal names for teh tribes.  In this particular case, the
"wild ass" allusion (see Comment to 16:2 [This is what comment on
16:12 says: "a wild ass of a man"  Like the wild ass among the
beasts, so are the Ishmaelites among men.  In their nature and
destiny they call to mind the sturdy, fearless, and fleet-footed
Syrian onager (Heb. "pere' "), who inhabits the wilderness and is
almost impossible to domensticate.  Jeremiah describes the wild
ass of the desert: "snuffing the wind in her eagerness, whose
passion none can restrain".  Hagar, the abused slave woman
subjected to the harsh discipline of her mistress, will produce a
people free and undisciplined.]) may be to the freedom and
independance of the Joseph tribes, which occupied an area that
had previously been sparesely populated, as is clearly implied in
Joshua 17:14-18.

	"spring...hillside"  Hebrew " `ayin, shur" may well be word
play concealing a reference to the Ishmaelites who sold Joseph to
Egypt, as related in Gen. 37:25, 28.  "The spring ( `ayin) on the
road to Shur" plays an important role in the birth narrative
about Ishmael (16:7), who is also described as "a wild ass"
(16:12).  Further, the following two verses here refer to hostile
archers, and Ishmael was indeed "a bowman" (21:20).  It is also
worht ntoing that both " `ayin" and "shur" are terms of "seeing"
and Hagar, mother of Ishmael, referred to the "Gos of Seeing",
who reassured her at "the Well of the Living One Who sees me"
(16:13).

	"hillside"  A poetic extension of the otherwise attested
meaning, "wall".