All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
As far as we know, the books of biography of the Prophet did not mention a specific date at which the Prophet started working in trade or the period that he spent in trade. What is confirmed, however, is that he was engaged in trade before he was commissioned as a Prophet.
The book entitled Khaatam An-Nabiyyeen authored by Abu Zahrah reads:
“If being an orphan did not overcome Muhammad in himself, as Allaah honored him and no one could have overcome him, and he was the dear beloved orphan, then Muhammad benefited from being an orphan that he learned how to be diligent in earning his living without relying on anyone else except on his Lord, so he benefited from the advantages of being an orphan, and he was spared from its disadvantages. It is confirmed that the Prophet began to rely on himself afterwards, as he started herding sheep as a boy, and when he was in his teenage years, he directed himself to the industry of the honorable people of Makkah, which is trade. History did not mention at which age he began to trade, but there are indications that he began at an early age.”
Allaah knows best.