Al-Adab Al-Mufrad, Hadith 109 ⓘ
Al-Hasan was asked about the neighbour and said, "The term 'neighbour' includes the forty houses in front a person, the forty houses behind him, the forty houses on his right and the forty houses on his left."
حَدَّثَنَا الْحُسَيْنُ بْنُ حُرَيْثٍ، قَالَ: حَدَّثَنَا الْفَضْلُ بْنُ مُوسَى، عَنِ الْوَلِيدِ بْنِ دِينَارٍ، عَنِ الْحَسَنِ، أَنَّهُ سُئِلَ عَنِ الْجَارِ، فَقَالَ: أَرْبَعِينَ دَارًا أَمَامَهُ، وَأَرْبَعِينَ خَلْفَهُ، وَأَرْبَعِينَ عَنْ يَمِينِهِ، وَأَرْبَعِينَ عَنْ يَسَارِهِ.
also referenced under: Book 6, Hadith 9 (In-Book) & Book 6, Hadith 109 (English)