Sahih Bukhari Volume 8, Book 74, Hadith Number 248.

Narated By Abu Said Al-Khudri: The Prophet said, ‘Beware! Avoid sitting on the roads.” They (the people) said, “O Allah s Apostle! We can’t help sitting (on the roads) as these are (our places) here we have talks.” The Prophet said, ‘ l f you refuse but to sit, then pay the road its right ‘ They said, “What is the right of the road, O Allah’s Apostle?” He said, ‘Lowering your gaze, refraining from harming others, returning greeting, and enjoining what is good, and forbidding what is evil.”