It was reported that Asmaa’ bint ‘Umays (may Allaah be pleased with her) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said to me:
“Shall I not teach you some words to say when you feel distressed? ‘Allaah, Allaah, Rabbee laa ushriku bihi shay’an (Allaah, Allaah, my Lord, I do not associate anything with Him).’”
Narrated by Abu Dawood, 1525; classed as saheeh by al-Albaani in Saheeh Abi Dawood, 1349.