Al-Kāfi

Hadith 1421
marriage
3- عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنِ الْحَسَنِ بْنِ مَحْبُوبٍ عَنِ الْعَلاءِ بْنِ رَزِينٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ سَأَلْتُ أَبَا جَعْفَرٍ (عَلَيْهِ السَّلام) أَيَتَزَوَّجُ الْمَجُوسِيَّةَ قَالَ لا وَلَكِنْ إِنْ كَانَتْ لَهُ أَمَةً.
3. A number of our people have narrated from Sahl ibn Ziyad from al-Hassan ibn Mahbub from al-‘Ala’ ibn Razin from Muhammad ibn Muslim who has said the following: “I once asked abu Ja‘far (a.s.), if it is lawful to marry a Zoroastrian woman. He (the Imam) said, ‘No, however, she can be his slave-girl.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī