It is narrated from Sayyiduna Mu'adh bin Anas al-Juhani (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever constructs a building without any injustice or transgression, or plants a tree without any injustice or transgression, it will be an ongoing reward for him as long as anyone from the creation of Allah benefits from it."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17545