Translation
(78) Good Manners and Form (Al-Adab)
كتاب الأدب
(59) Chapter: What sort of suspicion is allowed.
(59) باب مَا يَكُونُ مِنَ الظَّنِّ
Sahih al-Bukhari 6068 

Narrated Al-Laith:

`Aisha said "The Prophet (ﷺ) entered upon me one day and said, 'O `Aisha! I do not think that so-and-so and so-and-so know anything of our religion which we follow."'

حَدَّثَنَا ابْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، بِهَذَا وَقَالَتْ دَخَلَ عَلَىَّ النَّبِيُّ صلى الله عليه وسلم يَوْمًا وَقَالَ ‏ "‏ يَا عَائِشَةُ مَا أَظُنُّ فُلاَنًا وَفُلاَنًا يَعْرِفَانِ دِينَنَا الَّذِي نَحْنُ عَلَيْهِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 6068
In-book reference : Book 78, Hadith 98
USC-MSA web (English) reference : Vol. 8, Book 73, Hadith 94
  (deprecated numbering scheme)