يَا حَيُّ ، يَا قَيُّومُ ، بِرَ حْمَتِكَ أسْتَغِيثُ

Ya Hayyu Ya Qayyoom bi Rahmatika astagheeth

O Ever-Living, O Eternal, by Your Mercy I seek help.

[Sahih al-Hakim 1/545, Sahih al-Jami 4791, at-Tirmidhi – Sahih]
Anas (ra) reported that when the Prophet (saws) was distressed by something, he would say (the above)