Or HaChaim on Genesis 49:14/אור החיים על בראשית מ״ט:י״ד

1 יששכר חמור גרם, "Issachar is a bony donkey, etc." We learn in Nidah 31 that the meaning of the verse is that G'd had a hand in the conception of Issachar having guided Jacob's donkey to the tent of Leah on that night (Genesis 30,16). Just as Jacob had not remained in his regular abode that night, so Issachar, the son who had been conceived during that night, would be "crouching between boundaries." Inasmuch as Issachar is the model of a person who devotes his life to Torah study, Jacob alluded to the phenomenon that Yeshivah students have a habit of moving from place to place. Every action which is not proper produces consequences which reflect that impropriety. Leah's action appeared too forward for the conduct associated with the traditional way of life of Jewish women, even though her intention was wholly honourable. In spite of the discomfort associated with the lifestyle of the Yeshivah student, he does not let this diminish the effort he lovingly devotes to Torah study.

2וירא מנוחה כי טוב, "He observed that repose is good, etc." The reference is to the repose experienced in the Hereafter. The words כי טוב, refer to what happens after a person considers that all the pleasures available for the body in this world, such as eating fine food and drinking good wine, are all sensations which are devoid of an inherent value. They are meaningful only because the body, an empty vessel, needs to be filled up with food and drink as the Creator has decreed that it is incapable of existing without input of food and drink. As a result, once the body has absorbed enough food an drink, the very food and drink which provided these pleasurable sensations become revolting. This fact demonstrates that food and drink are not in themselves something desirable. Solomon makes that point in Proverbs 23,8 when he said: "once you have eaten your bread, you will vomit it;" he meant that when you have consumed all the bread of this world, the time will come when you vomit it as it will become repugnant for you to fill your mouth with it. The same applies to all the other pleasures this world has to offer, things which man is attracted to by his eyes. Once he examines these phenomena more thoroughly he will realise that they are only make believe, that they lack substance, and eventually he will develop a distaste for everything connected with the human body and its attractions. He will conclude that the real good can be found only in the Hereafter, the world which is all spirit. Jacob blessed Issachar by saying that he has realised that true repose is only in those regions. Issachar correctly evaluates the repose in the Hereafter as well as the relative pleasantness on earth, i.e. והארץ כי נעמה.

3When Jacob added ויט שכמו לסבול, "he bent his shoulder to bear (a burden)", this is a reference to the pain which is part of our earthly existence; ויהי למס עובד, "he turned himself into someone who serves the Lord as a form of paying tribute."

4Another meaning of these last words may be that in return for becoming a willing servant of the Lord, the rest of the population is obligated to pay מס some kind of tax to assure the Torah scholar of his livelihood. In the case of Issachar that would be Zevulun who was a seafarer putting much of his wealth at the disposal of Issachar. (compare previous verse).