Al-Kāfi - Volume 4 > One Becomes 111, in Ptikaf or Finds Hayd (menses)
Hadith #2

2ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ وَسَهْلِ بْنِ زِيَادٍ جَمِيعاً عَنِ ابْنِ مَحْبُوبٍ عَنْ أَبِي أَيُّوبَ عَنْ أَبِي بَصِيرٍ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ السَّلاَم) فِي الْمُعْتَكِفَةِ إِذَا طَمِثَتْ قَالَ تَرْجِعُ إِلَى بَيْتِهَا وَإِذَا طَهُرَتْ رَجَعَتْ فَقَضَتْ مَا عَلَيْهَا.

2. A number of our people have narrated from Ahmad ibn Muhammad from and Sahl ibn Ziyad all from ibn Mahbub from abu Ayyub from abu Basir who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘If a female in Ttikaf begins to experience Hayd (menses) she must go home; and after becoming clean return to complete Qada’ (compensatory ’Ttikaf) of what she owes.’”