Muhammad bin Mansoor narrates: We were once seated with Imam Bukhari (Rahmatullahi Alayh) in the musjid. One of those present noticed a speck of dirt on his own beard, so he dusted it off resulting in it falling onto the floor of the musjid. I noticed Imam Bukhari (Rahmatullahi Alayh) carefully watching that little speck of dirt as well as simultaneously watching the people, waiting for an opportune moment to pick it up without being noticed. Once he gauged that the people’s sight had turned away, he discretely picked it up and put it into his pocket. On leaving the musjid he removed it and discarded it outside. (Risalatul – Mustarshideen, pg. 155)
Lesson: Honouring and showing respect to the sailiant symbols of Islam results in the person himself being honoured. It was such acts of respect that added to the respect and honour of Imam Bukhari (Rahmatullahi Alayh).