This camel is considered to be a stray and it is reported that when
The Prophet (peace be upon him) was asked about
lost camels, he (peace be upon him) said, “What have you to do with it? Leave it alone, for it has its hooves and its water container (i.e. Its belly); it can reach water and eat trees until its owner finds it.”
(Agreed upon by Al-Bukhari and Muslim)
This Hadith indicates that it is not permissible to take a lost camel and that anyone who takes one is sinful. You therefore have to ask Allah for forgiveness and repent to Him.
If you do not know who its owner was, you should give out the price you sold it for or its equivalent - in terms of value - in banknotes as Sadaqah (voluntary charity) to the poor with the intention that it be on behalf of its owner. Whenever it happens that its owner comes, you should give him its price if he does not agree to the Sadaqah on his behalf; in which a case the Sadaqah will be considered from you. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.