In the charedi yeshivos I attended, I was taught that the tribe of Yissacher were sitting and learning in kollel, being supported by the tribe of Zevulun. Like much of what I was taught in these yeshivos, however, it turns out that this is not found in Tanach, and has far less support in Chazal or even the Rishonim than one is normally led to believe.
The Torah says the following about Yissacher and Zevulun:
Zevulun shall dwell by the seashore, he shall be a haven for ships, and his flank shall rest on Sidon. Yissachar is a strong-boned donkey, crouching among the sheepfolds; when he saw how good was the resting place, and how pleasant was the country, he bent his shoulder to the burden, and became an indentured laborer. (Gen. 49:14-15)Certainly, at a level of pshat, this means that Yissacher was working his land (and, as many people vociferously insist when one talks about the Six Days of Creation not necessarily referring to 144 hours, Ain mikra yotse midei peshuto). Thus, Rashbam explains "crouched among the sheepfolds" to refer to their being in "the borders of the city - plowing and working the land," as opposed to Zevulun, who were traveling overseas to engage in commerce.
Still, Chazal add an additional layer of interpretation. Here is what Chazal say about these verses:
Zevulun was busy with his merchandise trading (pragmatya - a Greek word that is the root of the English word "pragmatic") and would provide food for Yissacher, who was a Ben Torah… and when Moses came to bless the tribes, he preceded the blessing of Zevulun to that of Yissacher: “Rejoice, Zevulun, in your going out, and Yissacher in your tents” – Rejoice, Zevulun, in your going out, due to that which Yissacher is doing in the tents. (Midrash Bereishis Rabbah 72:5)But when it says that Zevulun was busy with trading "his" merchandise, whose merchandise is it referring to? The Midrash later explains that it is referring to Yissacher's merchandise:
Zevulun preceded Yissacher, because Zevulun was busy with merchandise trading and Yissacher was busy with Torah, and Zevulun came and provided him with food, therefore he preceded him. With regard to him, Scripture states, "It is a tree of life to those who support it." Yissacher would gather in (his produce) and Zevulun would bring it on ships and sells it, and bring Yissacher all his needs. (Midrash Bereishis Rabbah 99:9)
"Rejoice, Zevulun in your going out" - This teaches us that Zevulun was a merchant for his brother, and he would take [produce] from his brother and sell it to the gentiles, and take from the gentiles and sell to his brother." (Sifre, Vezos Habracha 13; similarly in Midrash HaGadol)It should first be stressed that this is the drash of the passuk, not the pshat. Incidentally, I recall once being in a shul where the depiction of the tribes on the Aron or windows showed a Torah for Yisschar, instead of a donkey. This stood in contrast to the depictions for the other tribes, which showed the pshat of the verses rather than the drush. I can't for the life of me remember which shul it was, but when searching on Google for pictures, I came across the one included in this post, which likewise shows a lion for Yehudah but a Torah for Yissacher!
But, in any case, the key point to note is as follows: These Midrashim do not say that the tribe of Yissacher were simply sitting in the beis hamidrash while Zevulun brought food for them. Instead, they say that Zevulun were assisting Yissacher by marketing their produce.
Now, there are other sources which just talk about Yissacher being busy with Torah and Zevulun providing them with sustenance. However, these may not conflict with the Midrashim cited above; it may be that they are simply less specific about how it took place. Midrash Bamidbar Rabbah 13:16 does imply that Zevulun was simply giving hand-outs, but it should be born in mind that Bamidbar Rabbah is of far later authorship (and thus less authority) than Sifre and Bereishis Rabba.
In any case, the position of Midrash Bereishis Rabba and Sifre, that Yissacher were farming their land, is also self-evident from the Torah itself. After all, Yissacher had land! They weren't just letting it lie fallow. They worked it and farmed it, and Zevulun marketed it for them, which freed up some of their time for Torah study.
Furthermore, consider this: Why was it only Zevulun that was helping Yissacher? Why didn't any of the other tribes want in on it? The logical answer is that Zevulun was uniquely suited to help them, because they had ships, which meant that they could market their produce for them.
The notion that the tribe of Yissacher did not work at all, aside from going against the plain meaning of the Torah, would go against the general philosophy that we find in the writings of Chazal and the Rishonim. Their view was that the ideal is for a Torah scholar to be self-supportive, but license was given for supporting those serving the community; see my monograph on "The Economics of Torah Scholarship in Medieval Jewish Thought and Practice." This is somewhat similar to the view of Rambam with regard to the nature of the financial aid that may be given to Torah scholars: the investment of funds, and assistance in business (see my post "The Truth About A Much-Abused Rambam").
Finally, what about the description of Yissacher bending his shoulder to the burden and being "an indentured laborer"? Rashi, following the Midrashic non-literal interpretation, explains it to refer to the tribe of Yissacher toiling in Torah and serving the people with Torah teachings. It should be noted that, in line with the standard outlook of the Rishonim and before the mystical innovations of R. Chaim of Volozhin, we see that serving the nation with Torah is interpreted as meaning teaching Torah, not learning Torah.
But Ibn Ezra gives a more pshat-oriented explanation of the verse. He explains that the tribe of Yissacher were not powerful men and didn't want to go out to war. They preferred to stay farming the land - and in place of serving in the army, they paid a special tax! Bet you weren't taught that in yeshivah!