The dealings of Nabi (sallalahu Alaihi wasallam) with Hadhrat Khadijah (Radhiallahu Anha) was one of Mudharabah i.e. a partnership where she supplied the capital and he supplied the labour, by selling her goods in Syria, in return for a percentage of the profit. With the returns of the sales, he would buy more goods for her and sell them in Makkah. The merchandise sold was general i.e. whatever could be procured at a good price, be it clothing, food or anything else.
With his uncle Abu Talib, Nabi (sallalah alaihi wasalam) acted as a labourer and helper. There is very little detail on this topic in the books of Hadith and Seerah. Whatever little details could be found were in Al-Bidayah Wan Nihayah, Seerah ibn Hisham, Seerah ibn Ishaq, Tabqaat ibn Sa’d etc.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai