The Scholars differed on whether or not there is a minimum duration to make ‘Itikaaf.
Shaikh Muhammad bin Hizaam (may Allah preserve him) wrote:
“The Minimum Duration for ‘Itikaaf
There is two opinions in regards to it:
The first: there is no limit for the minimum duration for it. It is the opinion of ash-Shafi’ee, Dawood, Ibn ‘Ulayyah, a narration from Ahmad, and the chosen opinion of Ibn ul-Mundhir and Ibn al-‘Arabi. So it is valid to do ‘Itikaaf even for one hour and there is a narration from Abu Haneefa regarding it.
The Second: that the minimum time for ‘Itikaaf is a day and night and it is the opinion of Malik and the well-known opinion of Abu Haneefah.
The strongest opinion is the first because ‘Itikaaf in the language occurs [if performed] for a small duration of time or a long one and the Legislator (Allah) did not set any boundary specifying it with. So it remains upon its origin. See: al-Majmoo’ (6/420), al-Irshaad print and Tafseer al-Qurtubi (2/333)”. End quote. [Ithaaf ul-Anaam (pg. 194)]
This is also the opinion of Ibn Hazam in al-Muhallah (5/179).
It is also the opinion of Shaikh Bin Baz (may Allah have mercy upon him). He said ‘Itikaaf does not have a minimum duration and can be done for an hour or two. Even if someone intends to sit for worship or to read [Quran] in the masjid, then it is a type of ‘Itikaaf. [See: Ta’leeq ‘ala Riyaadus-Saliheen (Tape no. 402)]
Also Shaikh Salih al-Fawzan (may Allah preserve him) was asked:
“Is the minimum duration for ‘Itikaaf a day and night as comes in the Hadith of Umar?”
“There is no fixed time, even if it be an hour. The Jurists say even an hour [counts as ‘Itikaaf] because there does not come a boundary for it in the Legislation” End translation. [Reference]
And this is the opinion of other Scholars as well.
So based on this, it is allowed to make ‘Itikaaf for a period of time, even it be an hour, due it linguistically being considered ‘Itikaaf and due to there not being a fixed duration in the Legislation.
Note: Shaikh Ibn ul-‘Uthaymeen (may Allah have mercy upon him) said:
“Whoever makes ‘Itikaaf for a specific time like one hour or two hours, and the one who says: “Every time you enter the masjid, intend ‘Itikaaf, then this is detested from him because it is not from the guidance of the Messenger sallallahu alayhi wa salam” End translation. [Sharh ul-Mumti’ (6/506)]
Faisal bin Abdul Qaadir bin Hassan