There is a Hadith which means that

Q 6: Is it permissible to pass in front of a person offering Salah (Prayer) at the Masjid (mosque)?

A: It is forbidden to pass in front of a person offering Salah at the Masjid, whether they have placed a Sutrah (barrier placed in front of a person praying) or not, based on the general prohibition in the Hadith which states: (Part No. 7; Page No. 83)  If the one passing in front of a person offering Salah were to know what (sin) is incurred upon them, they would have preferred to stand for forty (days, months, or years) than to pass in front of them. A group of Fuqaha' (Muslim jurists) excluded Salah at Al-Masjid Al-Haram (the Sacred Mosque in Makkah) from this ruling. They granted a Rukhsah (concession) for people to pass in front of a worshiper who is offering Salah at Al-Masjid Al-Haram based on the evidence reported from Kathir ibn Kathir ibn Al-Muttalib from his father, on the authority of his grandfather who said: I saw the Messenger of Allah (peace be upon him) offering Salah at Al-Hajar Al-Aswad (the Black Stone in a corner of the Ka`bah) and people were passing in front of him. According to another narration on the authority of Al-Muttalib, he said: I saw the Messenger of Allah (peace be upon him) when he finished the seven rounds of Tawaf (circumambulation of the Ka`bah), he stood opposite to the (Yemeni) Corner and the roofed section and offered two Raka`hs at the border of the place of Tawaf, with no barrier between him and people circumambulating the Ka`bah. Although the Isnad (chain of narrators) of this Hadith is Da`if (weak), it is supported by the Athar (narrations from the Companions) reported in this regard, and the general principles of Shari`ah that aim at removal of hardship, as forbidding passing in front of a person praying at Al-Masjid Al-Haram will most likely create difficulty and be hard to comply with.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family and Companions.