It is narrated from Sayyiduna Habib bin Maslamah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) "classed the Arab horse as Arab and the hybrid as hybrid."
Ahmad bin Abi Ahmad al-Jurjani, a resident of Hims, narrated it in this way from Hammad bin Khalid with a connected chain, whereas al-Shafi'i, Ahmad bin Hanbal and a group narrated it from Hammad with a broken (munqati') chain.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17961