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)." (ID)
English reference (ID): Vol. 3, Book 16, Hadith 2487 (ID)
Arabic reference (ID): Book 16, Hadith 2581 (ID)