Moments before Yaakov Avinu's petirah, he gathered his children and said (Bereishis 49:1), האספו, "Assemble yourself..." The Zohar (Bereishis p.234.) says that Yaakov instructed his children to assemble and daven with minyan.
There are many benefits earned from davening with a minyan. One benefit is that it is mesugal for parnassah. It states in parashas Mikeitz (42:3) לשבור עשרה יוסף אחי וירדו ממצרים בר, "Yosef's brothers – ten of them – went down to buy grain from Mitzrayim." Rashi asks why the Torah tells us that there were ten brothers. We can figure out, on our own, that ten brothers went down to Mitzrayim!
The Divrei Yisrael of Modzitz zy'a answers: The purpose of this trip was לשבור בר, to bring back food and parnassah for their families, and they knew that the success of their mission was dependent on their tefillos with a minyan because davening with a minyan is mesugal for parnassah.
It states (Shemos 23:25) אלוקיכם 'ה את ועבדתם מקרבך מחלה והסירותי מימיך ואת לחמך את ובירך, "You shall worship Hashem your G-d and He will bless your bread and your water, and I shall remove illness from your midst." The Rebbe of Radishitz zt'l teaches that ועבדתם means tefillah with a minyan. (That's why it is written in plural tense.) The pasuk says that davening with minyan results in parnassah and health.
The Meor VeShemesh writes, "The primary way to serve Hashem is together with the congregation. This applies to all avodas Hashem aspects: Torah, tefillah, etc ... In particular, one must be cautious to daven with a minyan. If he does so, he is guaranteed abundant parnassah, and there will be brachah in everything he does."
The Yismach Yisrael wrote the following letter to his chassidim, "I also request from the businessmen that they should always daven in the beis chassidim (beis medrash) and they should never miss. Even if they need to wait until ten people gather, they should wait, and in the meantime, they should study something. I guarantee that this will not cause them any loss, chalilah. On the contrary, it will bring a brachah into their parnassah. It will also train their children to go to the beis medresh twice a day. And when one goes into a perfume store, he becomes perfumed."
The final words of this letter tell another important reason to daven with a minyan. It is a mitzvah to be among good Yidden. When one enters a perfume store, he comes out smelling better, and when one goes to a beis medresh, he becomes stronger and better than before.
