Allāhumma lā saḥla illā ma ja`altahu saḥla
wa anta taj`alu ‘l-ḥazna idhā shi'ta saḥla.
O Allah, there is no ease other than what You make easy.
If You please You ease sorrow.
Reference:
Ibn Hibban in his Sahih (no. 2427), and Ibn As- Sunni (no. 351). Al-Hafidh
(Ibn Hajar) said that this Hadith is authentic. It was also declared
authentic by 'Abdul-Qadir Al-Arna'ut in his checking of An-Nawawi's
Kitabul-Athkarp. 106.