Whosoever left some optional things simply for the fear that some people may not be able to understand them and may fall into something more difficult

Narrated Aswad: Ibn Az-Zubair said to me, "Aisha used to tell you secretly a number of things. What did she tell you about the Ka`ba?" I replied, "She told me that once the Prophet (sallallahu 'alaihi wa sallam) said, 'O `Aisha! Had not your people been still close to the pre-Islamic period of ignorance (infidelity)! I would have dismantled the Ka`ba and would have made two doors in it; one for entrance and the other for exit." Later on Ibn Az-Zubair did the same.