Sheikh Salman al-Oadah
I`tikâf means to observe a retreat in the mosque. Allah refers to i`tikâf, saying: ‘…while you are in retreat in the mosques.” [Sûrah al-Baqarah (187)]
Consequently, the person observing i`tikâf should not go outside, but must stay within the confines of the mosque for the duration of the i`tikâf. The question remains: how long must this duration be to count as a valid i`tikâf?
The shortest time that a person can observe i`tikâf is a matter of disagreement among scholars. The majority of scholars hold the view that there is no minimum specified timeframe. Any time that a person spends in the mosque can be an observance of i`tikâf, even if it is only for an hour of the day. Some go so far as to recognize a stay of a few moments to be an observance of i`tikâf.
Other scholars disagree. They say that for a person to observe a valid i`tikâf, he must remain in the mosque for at least one day. Some of them say that remaining in the mosque for the duration of a night is sufficient.
The strongest view – and Allah knows best – is that if a person stays in the mosque longer than the usual amount of time, and the person spends this extra time in the mosque with the intention of observing i`tikâf, then it will count as a valid i`tikâf.
And Allah knows best.
Source: Islam Today