Mishkat al-Masabih 4 Prayer كتاب الصلاة 209

وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا صَلَّى أَحَدُكُمْ فَلْيَجْعَلْ تِلْقَاءَ وَجْهِهِ شَيْئًا فَإِنْ لَمْ يَجِدْ فَلْيَنْصِبْ عَصَاهُ فَإِنْ لَمْ يَكُنْ مَعَهُ عَصَى فَلْيَخْطُطْ خَطًّا ثُمَّ لَا يَضُرُّهُ مَا مَرَّ أَمَامه» . رَوَاهُ أَبُو دَاوُد وَابْن مَاجَه

Abu Huraira reported God’s Messenger as saying, “When one of your prays he should put something in front of his face, and if he can find nothing he should set up his stick; but if he has no stick with him he should draw a line, then what passes in front of him will not harm him.” Abu Dawud and Ibn Majah transmitted it.