Is i'tikaf (spiritual retreat in the mosque) prescribed at all times?

Question : But is it prescribed at all times without fasting, or is it not prescribed except in Ramadan and with fasting?

Answer : The apparent indication of the Sunnah is that it is not prescribed except in Ramadan, and although it is permissible at other times, it is not prescribed except in Ramadan. The evidence for this is that it is not recorded from the Prophet (peace and blessings be upon him) that he Shawwal, and as for its permissibility at other times, it is based on the hadith of 'Umar (may Allah be pleased with him) that he vowed to perform i'tikaf for a night in the Sacred Mosque or for a day, so the Prophet (peace and blessings be upon him) said to him, "Have you fulfilled your vow?" This indicates that it is permissible in other than Ramadan, but it is not prescribed except in Ramadan.