Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا مُعْتَمِرٌ، عَنْ أَبِيهِ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ لَمْ يَبْقَ مِمَّنْ صَلَّى الْقِبْلَتَيْنِ غَيْرِي.Narrated Anas:None remains of those who prayed facing both Qiblas (that is, Jerusalem and Mecca) except myself
From Sahih al-Bukhari, whose reports the scholars accept as authentic.