This hadith that was taught in one of my Islamic psychology classes and contains a powerful du’aa against anxiety:
Narrated Anas bin Malik:
The Prophet (ﷺ) used to say,
“O Allah! I seek refuge with You from worry and grief, from incapacity and laziness, from cowardice and miserliness, from being heavily in debt and from being overpowered by (other) men.”
Arabic: اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْهَمِّ وَالْحَزَنِ، وَالْعَجْزِ وَالْكَسَلِ، وَالْجُبْنِ وَالْبُخْلِ، وَضَلَعِ الدَّيْنِ وَغَلَبَةِ الرِّجَالِ
Transliteration: Allahumma inni a’udhu bika minal-hammi wal-huzni, wal-‘ajzi wal-kasali, wal-jubni wal-bukhli, wa dala‘id-dayni wa ghalabatir-rijal. (Reference: Sahih al-Bukhari 6369)
If what I have said is correct, it is from Allah ﷻ; and if it is wrong, then it is from myself and Shayṭān.
Assalaam Aleykum wa Rahmatullahi wa Barakatouh.