In sadness, anxiety or a hard situation, the sunnah gives precise words to say. Five authentic invocations, in Arabic, phonetics and English, each with its source, to go through the trial without being alone.
Allāhumma innī ʿabduk, ibnu ʿabdik, ibnu amatik, nāṣiyatī bi-yadik, māḍin fiyya ḥukmuk, ʿadlun fiyya qaḍā’uk, as’aluka bi-kulli-smin huwa lak, sammayta bihi nafsak, aw anzaltahu fī kitābik, aw ʿallamtahu aḥadan min khalqik, awi-sta’tharta bihi fī ʿilmi-l-ghaybi ʿindak, an tajʿala-l-Qur’āna rabīʿa qalbī, wa nūra ṣadrī, wa jalā’a ḥuznī, wa dhahāba hammī
O Allah, I am Your servant, son of Your servant and of Your maidservant. My forelock is in Your hand, Your judgement over me is carried out, Your decree upon me is just. I ask You by every name that is Yours, by which You have named Yourself, or which You revealed in Your Book, or which You taught to one of Your creatures, or which You kept with Yourself in the knowledge of the unseen, to make the Quran the spring of my heart, the light of my chest, the removal of my sadness and the departure of my worry.
Ahmad 3712 · authenticated by al-Albani (Silsila Sahiha 199)
Lā ilāha illa-Llāhu-l-ʿaẓīmu-l-ḥalīm, lā ilāha illa-Llāhu rabbu-l-ʿarshi-l-ʿaẓīm, lā ilāha illa-Llāhu rabbu-s-samāwāti wa rabbu-l-arḍi wa rabbu-l-ʿarshi-l-karīm
None has the right to be worshipped but Allah, the Mighty, the Forbearing. None but Allah, Lord of the Mighty Throne. None but Allah, Lord of the heavens, the earth and the Noble Throne.
Sahih al-Bukhari 6346 · Sahih Muslim 2730
In hardship; the Prophet ﷺ also recommended it morning and evening.
Allāhumma innī aʿūdhu bika mina-l-hammi wa-l-ḥazan, wa-l-ʿajzi wa-l-kasal, wa-l-bukhli wa-l-jubn, wa ḍalaʿi-d-dayni wa ghalabati-r-rijāl
O Allah, I seek refuge in You from worry and grief, incapacity and laziness, miserliness and cowardice, the burden of debt and being overpowered by men.
Sahih al-Bukhari 6369
Mounis reports and sources, in order: the Quran, then the Sunnah. It never gives rulings: for jurisprudence, refer to the people of knowledge.