Al-Kāfi

Hadith 1243
fatimahahl-al-baytburial
9ـ عَلِيُّ بْنُ مُحَمَّدٍ وَغَيْرُهُ عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ قَالَ سَأَلْتُ الرِّضَا (عَلَيْهِ السَّلام) عَنْ قَبْرِ فَاطِمَةَ (عليها السلام) فَقَالَ دُفِنَتْ فِي بَيْتِهَا فَلَمَّا زَادَتْ بَنُو أُمَيَّةَ فِي الْمَسْجِدِ صَارَتْ فِي الْمَسْجِدِ.
9. Ali ibn Muhammad and others have narrated from Sahl ibn Ziyad from Ahmad ibn Muhammad ibn Abu Nasr who has said the following: “I asked al-Rida (a.s.) about the grave of Fatima (a.s.). He said, “She was buried in her own house. When the Umayyads enlarged the Mosque it became part of the Mosque.”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī