Sayyidah Aishah (may Allah be pleased with her) narrates from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) said: "Jibril enjoined me regarding the neighbour up to forty houses, ten houses on each side." Isma'il said: To his right, to his left, in front of him and behind him.
(b) Ibn Shihab narrates from the Prophet (peace and blessings be upon him) as a mursal report: "Forty houses." Ibn Shihab was asked: How forty houses? He said: To his right, to his left, behind him and in front of him.
These two chains contain weakness; it is only known as a mursal report of Ibn Shihab al-Zuhri from the Prophet (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12612