It is narrated from Sayyiduna al-Sa'ib bin Khallad (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever frightens the people of Madinah, Allah will frighten him, and upon him is the curse of Allah, the angels and all the people; neither a voluntary act of worship nor an obligatory one will be accepted from him."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6601