Musnad Ahmad 337:8

Sulayman ibn Dawud al-Hashimi narrated to us, he said: Isma'il ibn Ja'far informed us, he said: Yazid informed me, from 'Abd al-Rahman ibn Abi Sa'sa'ah al-Ansari, that 'Ata' ibn Yasar informed him, that al-Sa'ib ibn Khallad, the brother of Banu al-Harith ibn al-Khazraj, informed him, that the Prophet, peace and blessings of Allah be upon him, said: "Whoever frightens the people of Medina unjustly, Allah will frighten him, and upon him shall be the curse of Allah, the angels, and all of mankind. Neither an obligatory act nor a supererogatory act will be accepted from him."