Surah Al-Baqara, Verse 185
Translation — Sahih International
The month of Ramadhan [is that] in which was revealed the Qur'an, a guidance for the people and clear proofs of guidance and criterion. So whoever sights [the new moon of] the month, let him fast it; and whoever is ill or on a journey - then an equal number of other days. Allah intends for you ease and does not intend for you hardship and [wants] for you to complete the period and to glorify Allah for that [to] which He has guided you; and perhaps you will be grateful.
Source
Kur'an-ı Kerim, Bakara Suresi 2:185
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/2-suresi-185-ayet