In the last 10 days of Ramazan many people follow the Sunnah of Prophet Muhammad (PBUH) by doing itikaf, residing in the masjid. There are many questions which are related to itikaf such as when are they allowed to leave Masjid or whether they can cut nails & comb hairs, etc.
Zakir Naik answered this question through the narrations of Prophet Muhammad (PBUH). Regarding cutting nails and combing hair he said it is allowed but the sanctity should be maintained by removing the unwanted hairs or nails.
He further said that those who are in itikaf are allowed to leave the mosque if need to toilet arises, or he has to take ghusul or if he needs food.
But nowadays iftar is served in the mosque and toilets and the place for wudhu are adjacent to the Masjid hence there is no such need to leave the mosque.
Similar question was asked to the scholars of Dawat-e-Islami who also said that if necessary Shariah allows the person in Itikaf to leave the mosque for ghusul.