At times of amazement or delight

Subḥānallāh!

(Glory is to Allah).

[ Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 1/210, 390, 414 and Muslim 4/1857. Hisn al-Muslim 240 ]

Allāhu Akbar!

(Allah is the Most Great)

[ Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 8/441. See also Al-Albani, Sahih At-Tirmidhi 2/103, 235, Ahmad 5/218. Hisn al-Muslim 241 ]