In Ayahs 45 and 153 of Surah Al-Baqarah, Allah (SWT) said:

O’ those who believe, seek help through patience (fasting) and Salaat/Salaah, and indeed that is burdensome and difficult except for humble ones. It is narrated from Imam Sadeq (AS) who said: (the word) Patience (in these Ayahs) refers to fasting. Therefore, whenever a person is inflicted with hardship and calamity, must fast, because Allah (SWT) said: Seek help from patience, meaning from fasting [1].

[1] Tafseer Nooral Thaqalayn, Aminul Islam Tabarsi, Vol. 1, Page 76, Hadith 12 & Al-Kashshaf, Zamakhshari, Vol. 1, Page 134.

Source: en.shafaqna.com