Maliks Muwatta Book 36, Hadith Number 26.
Section : Judgement on Bringing Barren Land into Cultivation.
Yahya related from Malik from Hisham ibn Urwa from his father that the Messenger of Allah, may Allah bless him and grant him peace, said, “If anyone revives dead land, it belongs to him, and the unjust root has no right.”
Malik explained, “The unjust root is whatever is taken, or planted without right.”