• I heard Ishaq say: "The line in front of the one praying is horizontal."
1102 - Muhammad ibn Nasr narrated to us, he said: Hassan ibn Ibrahim narrated to us, from Sufyan ibn Sa'id—regarding the line when one is in an open expanse of land—that it is: "Horizontal."
1103 - Ishaq ibn Ibrahim narrated to us, he said: Al-Muqri' informed me, he said: Sa'id ibn Abi Ayyub narrated to me, he said: Khayr ibn Nu'aym narrated to me, from Ata' ibn Abi Rabah, who said: "If you pray in a desert, then draw a line in front of you, and make it horizontal."
1104 - Amr ibn Dinar said—regarding the line—: "Like a bow."
1105 - Muhammad ibn Nasr narrated to us, he said: Hassan narrated to us, from al-Qasim ibn Marwan, from Amr ibn Qays al-Mula'i, that he said: "The line is vertical."
Chapter: One who prays without a sutrah (protective screen)
• I said to Ahmad: "A man prays in an open expanse of land, and there is nothing in front of him, nor did he draw a line?" He said: "It is more beloved to me that he does so." I said: "What if he does not do so?" He said: "It suffices him."
1106 - Muhammad ibn al-Wazir narrated to us, he said: Al-Walid ibn Muslim narrated to us, he said: And Salim and Zuhayr informed me that they heard Kathir ibn Kathir, from his father, from al-Muttalib ibn Abi Wada'ah, who said: "I saw the Messenger of Allah (peace be upon him) praying facing the Black Corner, and there was no sutrah between him and the people circumambulating, men and women."