What to say when alarmed

لَآ اِلٰهَ اِلَّا اللّٰهُ

There is no deity except Allah.

1. Sahih al-Bukhari, no. (3346), Sahih Muslim, no. (2880), Sunan at-Tirmidhi, no. (2187), Sunan Ibn Majah, no. (3935).