Spiritual Retreat: Making Up an Invalidated Iʿtikaf and Remaining in the Place of Iʿtikaf
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1741
If a muʿtakif invalidates his iʿtikāf by doing one of the things that renders an iʿtikāf invalid – which were mentioned in the previous rulings (masāʾil) – and if the iʿtikāf is an assigned obligation,[1] then based on obligatory precaution, he must make up the iʿtikāf [i.e. he must perform it belatedly as qaḍāʾ]. If the iʿtikāf is not an assigned obligation – for example, one makes a vow to perform iʿtikāf without assigning a time for it – it is obligatory that he start the iʿtikāf all over again. If it is a recommended iʿtikāf and one invalidates his iʿtikāf after the completion of the second day, then based on obligatory precaution, he must make up the iʿtikāf. And if one invalidates a recommended iʿtikāf before the completion of the second day, there is no obligation for him and he does not have to make it up.
x. A muʿtakif must remain in the place of iʿtikāf and he must not leave it except in cases where leaving is legally permitted.
-Ayatullah Sistani, Practical Laws of Islam, Spiritual Retreat (Iʿtikāf)
See the first footnote pertaining to Ruling 1731 for an explanation of this term.