Tribute, Spoils, and Rulership (Kitab Al-Kharaj, Wal-Fai' Wal-Imarah)
Dawud :: Book 19 : Hadith 3067
Narrated Sa'id ibn Zayd:
The Prophet (peace_be_upon_him) said: If anyone brings barren land into cultivation, it belongs to him, and the unjust vein has no right.