(25) باب قَوْلِ النَّبِيِّ صلى الله عليه وسلم " لاَ تَسْأَلُوا أَهْلَ الْكِتَابِ عَنْ شَىْءٍ "
Narrated Humaid bin 'Abdur-Rahman that he heard Mu'awiya talking to a group of people from Quraish at Al-Madina, and on mentioning Ka'b Al-Ashbar, he said, "He was one of the most truthful of those who used to talk about the people of the Scripture, yet we used to detect certain faults in his information."
Reference: Sahih al-Bukhari 7361
In-book reference: Book 96, Hadith 88
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 92, Hadith 459