The Ruling on I'tikaf (spiritual retreat in the mosque) in Other Than the Three Mosques

Question: From 'Abd al-'Aziz ibn 'Abd Allah ibn Baz to the honorable brother S. A. M. (may Allah keep him safe).
Peace be upon you, and Allah’s mercy and blessings, and after that:
I refer to your inquiry, registered with the Department of Scholarly Research and Ifta under number 4886 and dated 24/10/1408 AH, in which you ask several questions, including:
What is the authenticity of the hadith: ? And if the hadith is authentic, does it actually mean that there is no i'tikaf (spiritual retreat in the mosque) except in the three mosques?

Answer: I'tikaf (spiritual retreat in the mosque) is valid in other than the three mosques; however, it is a condition that congregational prayer be established in the mosque where one performs i'tikaf. If congregational prayer is not established in it, then i'tikaf is not valid in it, except if one vows to perform i'tikaf in the three mosques, in which case he is obligated to perform i'tikaf in them to fulfill his vow. May Allah guide everyone to what He is pleased with. And may peace and the mercy and blessings of Allah be upon you.
The General President of the Departments of Research
Scientific, Ifta, Da'wah, and Guidance