בראשית מט:יא אסרי לגפן עירה ולשרקה בני אתנו כבס ביין לבשו ובדם־ענבים סותה
“He binds his foal to the vine, and his ass's colt to the choice vine-branch. He has washed his garment in wine, and his mantle in the blood of grapes.” (Genesis 49:11)
So Jacob visualises משיח (the Messiah I.L.), and how does he see him? He sees the saviour of mankind, the conqueror of nations, not on a steed, but on a young ass's foal. The "ass" is always used to represent peaceful well-being, peaceful national greatness, whereas "steed" is used to represent military might. Similarly the ass is chosen from all the "unclean", animals, to express by פטר חמור the dedication of all one's movable possessions. It is the animal that carries people at a leisurely pace and bears his packs and baggage for him. Thus the Jewish conception of the power of kings is not to be represented by horses. The Jewish Kings were prohibited by the Torah להרבות סוס. A Jewish King was also not to be chosen until after ירושה וישיבה, after the complete conquest and settlement in the land, expressly not primarily for military purposes, and it was just in that that the sin of the people lay in Samuel's time, that they demanded a king to lead them in the wars defending the land, as Samuel reproached them Ch. XII. 12.ותראו כי־נחש מלך בני־עמון בא עליכם ותאמרו לי לא כי־מלך ימלך עלינו וה' אלהיכם מלככם . That is why here the one real true king, saving Israel and mankind appears onבני אתונו ,עירו. Two points are stressed with this picture painted here of the future time. The king of mankind does not ride on a charger, but on an ass, so he comes as the King of Peace, and he ties up his animal to a vine. If one can tie an animal, and especially an עיר, the lively mettlesome young donkey, to a vine, it is a sign of an infinitely increased development in nature (the vine stem growing like that of a tree ), and in general of immense prosperity and abundance. Abundance in an infinitely increased blessing in the world or nature, and peace in the world of mankind are the two signs that always characterise this final age in the mouth of our prophets. As long as the animal of peace is not placed in its true worth, the leaders of men always represented on horseback, on chargers, and as long as one does not tie up one's animals to vines, for so long are we still a long way off from the promised regeneration of the world of nature and the world of Man.
Rabbi Samson Raphael Hirsch, the Pentateuch, Genesis 49:11