Sahih Al Bukhari 1: Chapter 3, Hadith 120

(120) (What is said regarding) the memorization of the (religious) knowledge

حَدَّثَنَا إِسْمَاعِيلُ، ‏‏‏‏‏‏قَالَ:‏‏‏‏ حَدَّثَنِي أَخِي، ‏‏‏‏‏‏عَنْ ابْنِ أَبِي ذِئْبٍ، ‏‏‏‏‏‏عَنْ سَعِيدٍ الْمَقْبُرِيِّ، ‏‏‏‏‏‏عَنْ أَبِي هُرَيْرَةَ، ‏‏‏‏‏‏قَالَ:‏‏‏‏ "حَفِظْتُ مِنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وِعَاءَيْنِ، ‏‏‏‏‏‏فَأَمَّا أَحَدُهُمَا فَبَثَثْتُهُ، ‏‏‏‏‏‏وَأَمَّا الْآخَرُ فَلَوْ بَثَثْتُهُ قُطِعَ هَذَا الْبُلْعُومُ".

SAHIH HADITH:

Narrated Abu Huraira: I have memorized two kinds of knowledge from Allah's Apostle . I have propagated one of them to you and if I propagated the second, then my pharynx (throat) would be cut (i.e. killed).

REFERENCE:

Sahih Al Bukhari 1: Chapter 3, Hadith 120