Sahih al-Bukhari 4162
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · The Ghazwa of Al-Hudaibiya
Narrated Sa`id bin Al-Musaiyab:
حَدَّثَنِي مُحَمَّدُ بْنُ رَافِعٍ ، حَدَّثَنَا شَبَابَةُ بْنُ سَوَّارٍ أَبُو عَمْرٍو الْفَزَارِيُّ ، حَدَّثَنَا شُعْبَةُ ، عَنْ قَتَادَةَ ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ ، عَنْ أَبِيهِ ، قَالَ لَقَدْ رَأَيْتُ الشَّجَرَةَ، ثُمَّ أَتَيْتُهَا بَعْدُ فَلَمْ أَعْرِفْهَا . قَالَ مَحْمُودٌ ثُمَّ أُنْسِيتُهَا بَعْدُ.
That his father said, "I saw the Tree (of the Ar-Ridwan Pledge of allegiance and when I returned to it later, I was not able to recognize it. (The sub--narrator MahmiJd said, Al-Musaiyab said, 'Then; forgot it (i.e., the Tree).)"