Genesis 49:11

How beauteous is the King, the Meshiha who will arise from the house of Jehuda! He hath girded his loins, and descended, and arrayed the battle against his adversaries, Slaying kings with their rulers; neither is there any king or ruler who shall stand before him. The mountains become red with the blood of their slain; his garments, dipped in blood, are like the outpressed juice of grapes.

אסרי לגפן עירה, an עיר, young ass, needs to be tied to a single vine to load it with many grapes

ולשרקה בני אתונו, a repetition for literary purposes, similar to expressions such as יהודה וישראל, when both words are references to the same people, or as the expression איש תחת גפנו ותחת תאנתו, “each man under his grape vine and under his fig tree” This expression which occurs frequently in the Book of Kings, etc., simply describes the economic affluence of the people, not that each man will own fig trees and grape vines.

כבס ביין לבושו, after the grapes have been stamped on with the feet to squeeze out the juice and to store them in the wine-presses, the workers’ clothing has become stained in the process as described by Isaiah 63,2 מדוע אדום ללבושך ובגדיך כדורך בגת?, “Why is your clothing so red, your garments like his who treads grapes? The prophet continues there in verse 3: “I trod them down in My anger trampled them with My rage. Their lifeblood bespattered My garments and all My clothing was stained.” After completing the process described one can drink the wine. This is why Yaakov continued with חכללי עינים מיין ולבן שנים מחלב. Who are the ones whose eyes are darker than wine and whose teeth are whiter than milk- the answer is found in Proverbs 23,29-30 those who linger over wine and those who go in search of mixtures of wine.”

סותה, as in כסות, a kind of garment

אוסרי לגפן עירה, this is one of the things that help us recognise the Redeemer when he comes. 1) he will manifest himself as Messiah by a foal borne by a she-ass. (Zecharyah 9,9) The reason this indicates that he is the Messiah is that he does not arrive on a horse, an animal which is ready for battle, for war. The final battle involving the nations of the world will already have been fought and won by G’d at the time he will manifest himself. He will commence his reign when peace already prevails. 2) the fact that he will tie his ass to a גפן, a vine, will be a symbol that he is destined to rule over the Jewish people, the people who have been compared to a grape vine as stated in Chulin 92. The prophet Isaiah 5,7 also referred to the Jewish people as G’d’s vineyard.

ולשרקה בני אתונו, this is a reference to a third symbol by which the Messiah will be identified, that not only will he tie his ass to a vine but to a sorekah, a choice vine. The wine from such vine illuminates the eyes of the Just of their respective generations, something that cannot be said of an ordinary vine.

כבס ביין לבושו, the fourth sign identifying the Messiah is that he will be able to launder his garments in blood. He will have to do this as he will find many people who have been slain in the war preceding his coming, and he will assist in their burial. (compare Isaiah 63,2 מדוע אדום ללבושך “why are your garments so red?”) Another allusion to this is found in Psalms 110,6 ידין בגויים מלא גווית, “he works judgment on the nations piling up bodies.”

אסרי לגפן. The letter י in the word אסרי is an addition, similar to the letter י in Deuteronomy 33,15 שכני סנה, and other examples of a similar construction. Also the letter י in בני אתונו, is an addition. The entire expression ולשרקה בני אתונו is a duplication, seeing that the word שרקה means the same as גפן, perhaps a superior type of vine. The entire verse is a praise of the quality of the land apportioned to the tribe of Yehudah which yields such bountiful harvests that the farmer can tie his ass to the vine after having eaten from its grapes, without any worry. There are so many grapes on a single vine that they suffice to make up a full load for his ass. Similarly, there is so much wine that even if he were to launder his garments in wine instead of in water, he would not run short of wine. Yaakov repeats the theme once more in different words, saying: ובדם ענבים סותה, the expression דם ענבים refers to wine, the word סותה to garments. Naturally, this is an exaggeration permissible to poets.