Fasting the 30th of Shaʿbān Due to Clouds

Q: If the crescent of Ramaḍān is obscured on the 30th night of Shaʿbān, what is the ruling regarding the following day?

A: If the horizon is blocked by clouds or similar obstruction (dust, mountains, etc) on the 30th night of Shaʿbān, the following day is fasted with the intention that it is Ramaḍān, as a precaution.

This position was held by numerous Companions.

Its basis is the ḥadīth of Ibn ʿUmar, attributed to the Prophet ﷺ:

“The month is twenty-nine days. Do not fast until you see the crescent, and do not break the fast until you see it. If it is obscured from you, then fa-qdurū lahu.”

The phrase fa-qdurū lahu here is understood to mean “restrict it,” as in the verse:

Wa man qudira ʿalayhi rizquhu “And whoever is restricted in his provision…” (65:7)

Meaning: Shaʿbān is restricted to twenty-nine days.

Ibn ʿUmar acted upon this understanding. If the crescent was obscured, he would fast the following day.

Accordingly, the rulings connected to Ramaḍān apply to that day, including the obligation of make-up (qaḍāʾ) and expiation (kaffārah) where relevant, so long as it is not later established that the day was in fact from Shaʿbān.

And Allāh knows best.

Source: Sharh al-Muntaha, Mukhtasar al-Ifadat