Bukhari

Hadith Commentary:
What happened was that Suhayb (radi Allahu anhu) spoke the Roman language, but he would mention his father as an Arab, Sinan ibn Malik.
Upon this, Abdur Rahman (radi Allahu anhu) said to him, "Fear Allah and do not attribute yourself to someone other than your father."
Suhayb (radi Allahu anhu) replied that his language became Roman because, in his childhood, the Romans attacked, captured him, and took him away.
He was raised among them, and thus his language became Roman.
Otherwise, he was originally an Arab.
He said, "I do not lie and claim to be the son of someone else.
Even if I were to receive such and such wealth, I would not do this."
From this hadith, Imam Bukhari (rahimahullah) deduced that the ownership of disbelievers is valid and recognized, because Ibn Jud'an purchased Suhayb (radi Allahu anhu) and then freed him.
There are many virtues of Suhayb (radi Allahu anhu),
which will be found in detail elsewhere.
He was very generous in feeding others and used to say that he heard this hadith from the Prophet (sallallahu alayhi wa sallam): "The best among you is the one who abundantly feeds those who have a right."

Hadith Commentary:
(1)
This narration is extremely concise.
The actual incident is as follows: Suhayb (radi Allahu anhu) was originally an Arab.
His father was from the tribe of Namir and his mother from Banu Tamim.
Both of these tribes are Arab.
Suhayb (radi Allahu anhu) was kidnapped in his childhood by someone and sold into the hands of the Romans; his upbringing took place in the Roman region.
Because of this, he spoke Arabic with a Roman accent and manner.
At the time of his abduction, he was conscious enough to know among which people he was born and among which people he was raised.
The tribe of Kalb bought him from the Romans, and then Ibn Jud'an bought him from them and set him free.
After returning to Arabia, when he expressed his lineage and ancestry, Abdur Rahman ibn Awf (radi Allahu anhu) expressed doubt regarding his statement.
At that time, Suhayb (radi Allahu anhu) gave the clarification which is mentioned in the hadith.
It is mentioned in Al-Mustadrak of Al-Hakim that Umar (radi Allahu anhu) also had a similar conversation with Suhayb (radi Allahu anhu), so he explained that he was from Namir ibn Qasit, but in childhood he was kidnapped and sold into the hands of the Romans, and his upbringing took place among the Romans, which is why he spoke Arabic in their accent and manner.
(Al-Mustadrak lil-Hakim: 398/3) (2)
The purpose of Imam Bukhari (rahimahullah) is that the ownership of the disbelievers and polytheists is valid and will be considered, because Ibn Jud'an bought him and then set him free.
On this basis, the transactions of buying and selling, manumission, gifting, etc., by disbelievers will be considered valid.
It will not be rejected merely on account of their disbelief.