It was narrated from Abu Sa'eed Al-Khudri that the Messenger of Allah (ﷺ) said:
"The land around a well (that is considered to be part of it) is the length of the well rope (in all directions)." (RU)
English reference (RU): Vol. 3, Book 16, Hadith 2487 (RU)
Arabic reference (RU): Book 16, Hadith 2581 (RU)