A man passing in front of one praying: whether he turns him back

Abu Abd al-Rahman Baqi bin Makhlad narrated to us; he said: Abu Bakr Abdullah bin Muhammad bin Abi Shaybah narrated to us; he said:

Al-Aswad said: "If anyone started to pass in front of Sayyiduna Ibn Mas'ud (may Allah be pleased with him) while he was praying, he would try his utmost to stop him, and he would say: 'Someone passing in front of the one praying spoils half of that man's prayer.'"

Al-Sha'bi said: "If someone starts to pass in front of you, do not stop him."