Sayyiduna Jabir (may Allah be pleased with him) said: A slave came and pledged allegiance to the Prophet (peace and blessings be upon him) on emigration (hijrah). He (peace and blessings be upon him) did not know that he was a slave. His master came wanting him (back), so the Prophet (peace and blessings be upon him) said: "Sell him to me." He (peace and blessings be upon him) bought him for two black slaves. After that he (peace and blessings be upon him) did not take allegiance from anyone until he had asked whether he was a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10522
Sayyiduna Anas (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) bought Sayyidah Safiyyah (may Allah be pleased with her) from Dihyah al-Kalbi (may Allah be pleased with him) for seven slaves.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10523
Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) was asked about buying one camel for two, and he said: "Sometimes one camel is better than two camels."
(b) Sayyiduna Rafi' bin Khadij (may Allah be pleased with him) bought one camel for two; he handed over one and said: "I will bring you the other one tomorrow morning, at ease."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10524
Sa'id bin al-Musayyib (may Allah have mercy on him) said: There is no usury in animals; but in animals the following are forbidden: (1) al-madamin (the young in the female's womb), (2) al-malaqih (the camel's mating), (3) habal al-habalah (that a female gives birth, and then that offspring becomes pregnant and gives birth).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10525
Salamah bin Alqamah narrates from Muhammad bin Sirin (may Allah have mercy on him) that he was asked: What about buying iron for iron? He said: Allah knows best; but they used to buy one coat of mail for several coats of mail.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10526
Ibrahim (may Allah have mercy on him) said: There is no harm in an advance sale (salaf) in copper coins (fulus). Sa'id al-Qaddah (may Allah have mercy on him) also said: There is no harm in an advance sale (salaf) in copper coins.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10527