The Roman Captive
Suhayb ibn Sinan was an Arab from the tribe of al-Namir ibn Qasit, but captured as a child during a Byzantine raid and taken to Rome (or Byzantine Syria). He grew up speaking Roman (Greek/Latin) and Arabic and eventually made his way back to Arabia as a free man. In Mecca he built wealth through commerce.
This dual background — Arab birth, Roman upbringing, Meccan commerce — gave him his famous surname: al-Rumi (the Roman).
The Transaction
When he sought to emigrate to Medina, Qurayshi men blocked his path: he was wealthy, and they were not going to let his wealth leave Mecca. He offered them a deal: take everything he had — his gold, his silver, his goods, his house — and let him go.
They accepted. He arrived in Medina with nothing but his clothes.
When the Prophet saw him coming, he said: “Rabih al-bay’! Rabih al-bay’!” — “The transaction has profited! The transaction has profited!” And the verse was revealed (2:207): “And of the people is he who sells himself, seeking means to the approval of God. And God is kind to [His] servants.”
The Implication
What Suhayb gave was replaceable; what he kept was not. The tradition reads his act as the prototype of the spiritual transaction: giving the perishable for the imperishable. His epithet in the tradition is man sha’a fa’l-ya’mal (whoever wishes, let him emulate this).
See also: Seerah Khabbab Ibn Al Aratt, Seerah Julaybib, Seerah Al Arqam Ibn Abi Al Arqam, Seerah Abdallah Ibn Masud, Seerah Badr