Sayyiduna Abu Hurayrah (may Allah be pleased with him) relates that the Messenger of Allah (peace and blessings be upon him) said: "When a person prays, let him place something in front of himself. If he does not find anything, let him set up a staff, and if he does not have a staff with him either, let him draw a line. Then nothing that passes in front of him will harm him."
In the same way, Rawh bin al-Qasim and Ibn Uyaynah, in one of the two narrations, and Sufyan al-Thawri narrated this report from Isma'il.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3466
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When one of you prays, he should place something in front of himself. If he cannot find anything, then let him at least draw a line; then nothing that passes in front of him will harm him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3467
Humayd bin al-Aswad also narrated it from Isma'il bin Umayyah, from Abu Amr bin Muhammad bin Hurayth bin Sulaym, from his father, from Sayyiduna Abu Hurayrah (may Allah be pleased with him), from the Prophet (peace and blessings be upon him), with the same wording as the hadith of Bishr.
Wuhayb and Abd al-Warith narrated it from Isma'il, from Abu Amr bin Hurayth, from his grandfather Hurayth. Abd al-Razzaq narrated it from Ibn Jurayj, who heard Isma'il, from Hurayth bin Ammar, from Abu Hurayrah, in abridged form. Ibn Uyaynah narrated it, in the narration of al-Shafi'i (may Allah have mercy on him), al-Humaydi and a group of others from him, from Isma'il bin Umayyah, from Abu Muhammad bin Amr bin Hurayth, from his grandfather Hurayth al-Udhri, from Sayyiduna Abu Hurayrah (may Allah be pleased with him); then it was reported from him (Ibn Uyaynah) that he was in doubt about it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3468
Imam Abu Dawud (may Allah have mercy on him) says: I heard Imam Ahmad bin Hanbal (may Allah have mercy on him) describe the line; he said: "Like this," meaning widthwise, in the curved shape of the crescent moon.
Imam Abu Dawud (may Allah have mercy on him) says: I heard Musaddad, who related on the authority of Ibn Dawud that the line should be drawn lengthwise.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3469
Bishr bin Musa relates: I asked al-Humaydi (may Allah have mercy on him) about the line, and he showed me by gesturing, that is, like the shape of the crescent moon.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3470