And from him, from Muhammad ibn al-Walid, from Aban ibn Uthman, from Yahya ibn Abi al-Ala al-Razi, from Abu Abdillah عليه السلام, peace be upon him:
Imam عليه السلام said: “There is no seclusion for worship (itikaf) except in a mosque of congregation.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 363