Sforno on Genesis 49:11/ספורנו על בראשית מ״ט:י״א

1אוסרי 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.

2ולשרקה 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.

3כבס 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.”