What financial arrangement did Rambam have with his jeweler brother?

Question

I was taught in yeshiva that as a young man, Rambam just studied Torah and was supported by his brother, who was a jewel merchant. Then his brother died at sea, so Rambam became a physician.

Recently someone told me that no, Rambam was never a "professional Torah student." His brother did the hard work of sailing the seas to obtain the jewels wholesale, and Rambam had a fairly calm job retailing them -- but he was still working.

Does anyone have sources on this, please?

Answer 1

These Hebrew sites cite a letter from Rambam to Eliyahu the Dayan (Igrot Rambam, Rav Shilat Press, Volume I p. 311; emphasis added):

והרעה הגדולה שבאה עליי באחרונה, ...והיא פטירת הצדיק, שטבע בים הודו ובידו ממון רב לי ולו ולאחרים והניח בת קטנה ואלמנתו אצלי..והוא היה האח. והוא היה התלמיד והוא היה הנושא ונותן בשוק ומרוויח, ואני הייתי יושב לבטח...והלך לחיי העולם, והניחני נבהל בארץ נוכריה.

And the greatest tragedy that recently befell me was the death of the righteous one who drowned in the Indian Ocean while holding a great deal of property of mine, his, and others', leaving me with his young daughter and widow, namely my brother. He was a student, he would do business in the markets and make profits while I dwelled securely ... he has gone to Eternal Life, leaving me confounded in a strange land.

So his brother had "money of his", "and did business while leaving me secure." I guess there are several ways that can be read:

• He had money that he had -- pledged to me? Owed me? Because he was supporting me?
• He had money that I had invested with him.
• He "left me secure" because he paid all the bills, or because he took care of the major risks?

Answer 2

See here:

However, some ask, did not the Rambam do precisely that? Did he not learn Torah while his brother, David, worked as a merchant and supported him? Only after his brother died tragically did Rambam start working.

...

The answer seems to be that this is not true.

...

It was customary in merchants' families that one member, usually a father or elder brother, stayed put and the others traveled. Labrat and Judah (like Moses and David Maimonides later) had divided the family business between themselves in such a way.

It seems that this rests on supposition, based on what was common in those days.