Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "It is not lawful for a Muslim (the narrator is unsure whether the words are:) for a believer to alarm a Muslim."
Al-Bazzar recorded it. Its chain contains Abd al-Karim Abu Umayyah, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحدود والديات / 10528