What is the authenticity of the hadith: "Indeed, I saw the pillar of the Book being taken from beneath my pillow, and I looked, and behold, it was a brilliant light that was directed towards Sham (Syria). Verily, faith, when tribulations occur, will be in Sham"?

This is an authentic hadith (definition) with multiple chains of transmission, and it has been authenticated by a number of imams, including Al-Bayhaqi, Al-Mundhiri, Ibn Hajar, Al-Albani, and the verifiers of Al-Musnad.

The purport of the hadith is that the Prophet, peace and blessings be upon him, saw in a dream the pillar of the Book (or Islam) being carried from under his head and taken towards Al-Sham, which indicates that faith and security will be in Al-Sham when tribulations occur, and that Al-Sham is the stronghold of the believers, and therein resides the victorious group that adheres to the truth.