Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.018C.

Section : One should avoid shaded places and those places where people walk and gather.

Abu Hurairah reported that the Messenger of Allah, upon whom be peace, said, “Beware of those acts which cause others to curse.” They asked, “What are those acts?” He said, “Relieving yourself in the people’s walkways or in their shade.” This hadith is related by Ahmad, Muslim and Abu Dawud.