Sayyiduna al-Miqdad bin al-Aswad (may Allah be pleased with him) relates: I never saw the Messenger of Allah (peace and blessings be upon him) pray directly facing a piece of wood, a pillar or a tree; rather, he (peace and blessings be upon him) would keep it towards his right or left side and would not place it in the middle (that is, he would keep it in line with his right or left shoulder, not in front of his face).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3472
Duba'ah bint al-Miqdam (may Allah have mercy on her) narrates from her father, who said: I saw the Messenger of Allah (peace and blessings be upon him) praying towards a sutrah, and he (peace and blessings be upon him) would keep it in line with his right or left shoulder and would not place it in the middle.
Only al-Walid bin Kamil al-Bajali al-Shami narrated this hadith, and al-Bukhari said: He has strange (unusual) narrations.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3473