Language:
كتاب فى اللقطة
45  
Lost Things Picked up by Someone (Luqatah)
(10)
Chapter: Should one pick up a fallen thing?
(10)
باب هَلْ يَأْخُذُ اللُّقَطَةَ وَلاَ يَدَعُهَا تَضِيعُ، حَتَّى لاَ يَأْخُذَهَا مَنْ لاَ يَسْتَحِقُّ
Sahih al-Bukhari 2437b

Narrated Salama:

the above narration (Hadith 616) from Ubai bin Ka`b: adding, "I met the sub-narrator at Mecca later on, but he did not remember whether Ka`b had announced what he had found one year or three years."

حَدَّثَنَا عَبْدَانُ، قَالَ أَخْبَرَنِي أَبِي، عَنْ شُعْبَةَ، عَنْ سَلَمَةَ، بِهَذَا قَالَ فَلَقِيتُهُ بَعْدُ بِمَكَّةَ، فَقَالَ لاَ أَدْرِي أَثَلاَثَةَ أَحْوَالٍ أَوْ حَوْلاً وَاحِدًا‏.‏
Reference : Sahih al-Bukhari 2437b
In-book reference : Book 45, Hadith 13
USC-MSA web (English) reference : Vol. 3, Book 42, Hadith 617
  (deprecated numbering scheme)