It is narrated from Sayyiduna Abu Shurayh that once the Prophet (peace and blessings be upon him) repeated this statement three times, swearing an oath each time: "That person cannot be a believer." The companions asked: "O Messenger of Allah! Who is that person?" He replied: "The one whose neighbors are not safe from his harms." The companions asked the meaning of "harms" (boaiq), so he said: "Evil."
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16372