Narrated Abdullah Ibn Masood (RA): The Messenger of Allah (ﷺ), said, "If a servant is faced with any anxiety or distress, then say:

اَللَّهُمَّ إِنِّي عَبْدُكَ، وَابْنُ عَبْدِكَ، وَابْنُ أَمَتِكَ، نَاصِيَتِي بِيَدِكَ، مَاضٍ فِيَّ حُكْمُكَ، عَدْلٌ فِيَّ قَضَاؤُكَ، أَسْأَلُكَ بِكُــــلِّ اسْمٍ هُوَ لَكَ، سَمَّيْتَ بِهِ نَفْسَكَ، أَوْ أَنْزَلْتَهُ فِي كِتَابِكَ، أَوْ عَلَّمْتَهُ أَحَدًا مِنْ خَلْقِكَ، أَوِ اسْتَأْثَرْتَ بِهِ فِي عِلْمِ الْغَيْبِ عِنْدَكَ، أَنْ تَجْعَلَ الْقُرْآنَ رَبِيعَ قَلْبِي، وَنُورَ صَدْرِي، وَجَلَاءَ حُزْنِي، وَذَهَابَ هَمِّي

Allaahumma 'innee 'abduka, wabnu 'abdika, wabnu 'amatika, naasiyatee biyadika, maadhin fiyya hukmuka, 'adlun fiyya qadhaa'uka, 'as'aluka bikulli ismin huwa laka, sammayta bihi nafsaka, 'aw 'anzaltahu fee kitaabika, 'aw 'allamtahu 'ahadan min khalqika, 'awista'tharta bihi fee 'ilmil-ghaybi 'indaka, 'an taj'alal-Qur'aana rabee'a qalbee, wa noora sadree, wa jalaa'a huznee, wa thahaaba hammee

O Allah, I am Your slave and the son of Your male slave and the son of your female slave. My forehead is in Your Hand (i.e. you have control over me). Your Judgment upon me is assured and Your Decree concerning me is just. I ask You by every Name that You have named Yourself with, revealed in Your Book, taught any one of Your creation or kept unto Yourself in the knowledge of the unseen that is with You, to make the Qur'an the spring of my heart, and the light of my chest, the banisher of my sadness and the reliever of my distress. Allah will surely remove his worries and troubles and replace them with joy. ”It was asked, O Messenger of Allah! Shall we not learn it? ' The Prophet (ﷺ) said, “Of course! Anyone who hears this should memorize it.”

Reference: Sahih (Albani) Silsila Sahihah: 1/337