It is preferred for the one who is praying to place a sutrah (or some sort of partition) in front of him in order to keep others from passing in front of him and to keep his eyesight from going behind this partition.
Abu Sa’id reports that the Prophet sallallahu alehi wasallam said: “When one of you prays, he should pray toward his sutrah and he should be close to it.” This is related by Abu Dawud and Ibn Majah.
Ibn ‘Umar relates that “when the Prophet sallallahu alehi wasallam went out to pray salatul ‘id, he asked for a spear and placed it in front of himself and he offered salah toward it and the people prayed behind him. And he would do that while he was traveling so that those in authority [for the affairs of the Muslims] would also do this.” This is related by al-Bukhari, Muslim, and Abu Dawud.
The Hanafi and Maliki scholars are of the opinion that one should place a sutrah in front of him only if he fears that someone may pass in front of him; if he does not fear that someone will pass in front of him, it is not desirable for him to place a sutrah in front of himself. This opinion is based on the hadith of Ibn ‘Abbas who said that the Prophet sallallahu alehi wasallam prayed in an open area and there was nothing in front of him. This is related by Ahmad and Abu Dawud. Al-Baihaqi related it and said: “It is supported by a report from al-Fazhl Ibn ‘Abbas with a reliable chain of transmitters.”