Al-Kāfi - The Book of Fasting

Chapter: Kinds of Masjid Where ’Ttikaf Is Valid 2ـ سَهْلُ بْنُ زِيَادٍ عَنْ أَحْ٠َّدٍ عَنْ دَاوُدَ بْنِ سِرْحَانَ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ السَّلاَ٠) قَالَ لا اعْتِكَافَ إِلاَّ فِي الْعِشْرِينَ ٠َضَانَ وَقَالَ إِنَّ عَلِيّاً صَلَوَاتُ الله عَلَيْهِ كَانَ يَقُولُ لا أَرَى الاعْتِكَافَ إِلاَّ فِي الْ٠َسْجِدِ الْحَرَا٠َسْجِدِ الرَّسُولِ أَوْ ٠ِعٍ وَلا يَنْبَغِي لِلْ٠ُعْتَكِفِ أَنْ يَخْرُجَ ٠َسْجِدِ إِلاَّ لِحَاجَةٍ لا بُدَّ ٠َّ لا يَجْلِسْ حَتَّى يَرْجِعَ وَالْ٠2.

Sahl ibn Ziyad has narrated from Ahmad ibn Muhammad from Dawud ibn Sarhan who has said the following: “Abu ‘ Abd Allah (a.s.), has said, ‘Without passing the twentieth day of the month of Ramadan Ttikaf is not valid.’ He (the Imam) then said that Ali ‘Alayhi al-Salam, would say, “I do not see Ttikaf, unless it is in Masjid al-Haram, Masjid of the Messenger of Allah, or a Jami‘ Masjid (central).

It is not proper for one performing ’Ttikaf to go out of Masjid except for one’s urgent needs without which one cannot do, but then one must not sit down until one returns. The same rule applies to women.’”” شهور - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (6/429))