Al-Sha'bi narrates from Sayyiduna Umar (may Allah be pleased with him) that an Arab shall not be enslaved.
(b) Al-Zuhri narrates from Sa'id bin al-Musayyib (may Allah have mercy on him) that a slave may marry a slave-girl, and his children will be slaves; an Arab may also marry a slave-girl, but his children shall not be enslaved; he is responsible for paying their value.
Imam al-Shafi'i (may Allah have mercy on him) says: Whoever does not consider this hadith established from the Prophet (peace and blessings be upon him) holds that Arabs and non-Arabs are equal: wherever slavery applies to a non-Arab, it applies to an Arab as well, and Allah knows best. Al-Rabi' says: Imam al-Shafi'i (may Allah have mercy on him) adopts this view.
The Shaykh says: As for the narration on this from the Prophet (peace and blessings be upon him), Imam al-Shafi'i (may Allah have mercy on him) mentioned it only in his old (qadim) works.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18068