What is the ruling on praying the regular Sunnah prayer of Fajr and what follows from it, and is it better to pray the Sunnah at home then go to the mosque, or to go to the mosque and pray the obligatory prayer only? And what is the ruling on a worshiper praying the obligatory prayer behind someone who is praying the Sunnah prayer, and should the worshiper lead in this case silently or audibly?

The statement that the Fajr obligatory prayer is not valid without its Sunnah (supererogatory prayer) is incorrect. When there is a conflict between performing the obligatory prayer at home with its Sunnah and performing the obligatory prayer in congregation at the mosque, prioritizing prayer at the mosque is more appropriate. This is due to the differing opinions among scholars regarding the obligation of congregational prayer, and because the Sunnah can be made up after the obligatory prayer or after sunrise. And if the Iqamah (call to commence prayer) is given, only the obligatory prayer should be performed, based on the Prophet's (peace be upon him) saying: "When the Iqamah for prayer is given, there is no prayer except the obligatory one."

If one is at home and knows that if he starts the Sunnah prayer, he will miss a rak'ah with the Imam, then it is better to go directly to the mosque and make up the Sunnah after the obligatory prayer or after sunrise.

One should not rush when going to the mosque, based on the Prophet's (peace be upon him) saying: "When the Iqamah for prayer is given, do not come to it rushing, but come to it with tranquility."

It is permissible to follow in prayer someone who is performing the Sunnah prayer while you are performing the obligatory prayer. The one praying the Sunnah should recite silently, but if he recites audibly, his prayer is still valid.