It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: The protected area (harim) of a well consists of forty cubits around it, and all of it is for the camels, goats, travelers, and those who come first to drink, and no one should be prevented from using extra water so that surplus grass may be withheld through it.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10411
Hadith Gradingحکم دارالسلام:إسناده صحيح، والرجل المبهم فى إسناده هو ابن سيرين