Is it permissible for a worshipper to conceal his knowledge that the dawn call to prayer (adhan al-fajr) is made before its actual time, and to pray the obligatory prayer alone at home after the correct time, knowing that he prays in the mosque with the intention of performing the Sunnah prayer?

The Shari'ah has tied the beginning of the Fajr prayer time to visual observation, not to the calculation of the sun's angle of depression, and this is accessible to all people. Indeed, the Shari'ah has considered the light visible to the naked eye and extending across the horizon from north to south.

Relying on the sighting of the crescent moon instead of astronomical calculation removes hardship from the "illiterate nation" (ummah ummiyyah) that does not write or calculate, as stated in the noble prophetic tradition: "Indeed, we are an illiterate nation; we do not write or calculate." Some scholars have held that this ruling remained even if there were those who knew calculation.

The wisdom behind this is clarified by the fact that when it comes to counting during unconsciousness, all responsible individuals are equal, thus eliminating disagreement and dispute.

The assertion that it is obligatory to refer to people of calculation (astrologers) is an invalid doctrine, and the Shari'ah has prohibited delving into the science of stars.

Therefore, whoever sees the true dawn prays, and whoever does not see it does not pray until he sees it, or until its appearance becomes highly probable in his estimation. And whoever finds it difficult to know the legal signs for the five prayers should ask the people of religious knowledge.