O Allah, I ask You for tranquility and peace of mind. — Anxiety
اللَّهُمَّ إِنِّي أَسْأَلُكَ السَّكِينَةَ وَالطُّمَأْنِينَةَ
Transliteration: Allaahumma innee as'alukas-sakeenata wat-tuma'neenah
Translation: O Allah, I ask You for tranquility and peace of mind.
Reference: General supplication