It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said: "Jibril kept on enjoining me to treat the neighbour well, until I thought that he would even make him an heir."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13224