Narrated Abu Huraira (rad):
Allah’s Messenger (ﷺ) said: “Safeguard yourselves from the two matters which cause accursing that befalls the one who relieves himself on people’s path-ways and under the shades.” [Reported by Muslim].

Narrated Mu’adh (rad):
He said: “Guard against the three things which cause curse (i.e.) defecating at the watering places, on the roadbeds and in the shades.” [Reported by Abu Dawud]

Ahmad reported from Ibn Abbas (rad) that defecation is prohibited also at the place where water collects. [And both the two (i.e. the previous and this Hadiths) have weakness].

At-Tabarani also narrated on the authority of Ibn ‘Umar (with a weak chain of narrators), the prohibition of relieving oneself under fruit trees and beside the bank of a flowing river.