Is it obligatory to form the intention the night before for fasting Ramadan, knowing that the intention is renewed daily in the heart? And does the Isha prayer count as part of the night? And what is the ruling on supererogatory fasting?

The majority of scholars (Hanafis, Shafi'is, and Hanbalis) stipulate the intention (niyyah) to be formed each night for the validity of the Ramadan fast. However, the Malikis (and one narration from Ahmad) hold that a single intention suffices for the entire month of Ramadan and for any obligatory continuous fast that falls under its ruling.

According to the majority view, merely having the thought of fasting in one's heart at night is sufficient for the intention, and night begins at sunset. As for voluntary fasting (Nafl), the majority of scholars do not require the intention to be formed from the night.