The World Federation One Stop Fiqh

Ruling 1727

While a muʿtakif is fasting – i.e. from the time of ṣubḥ prayers until the time of maghrib prayers – everything that invalidates (i.e. makes bāṭil) a fast also invalidates iʿtikāf. Therefore, a muʿtakif must refrain from intentionally (ʿamdan) doing the things that invalidate a fast.2

2  See Ruling 1551 for a list of the things that invalidate a fast.