What Is al-Lawh al-Mahfuz?
Question

Could you explain in detail including tafsir of the great scholars of Islam the meaning of ‘al-Lawh al-Mahfuz’ mentioned in the Quran (85:22)? Jazakallahu khairan!
Praise be to Allah.What is al-Lawh?
Ibn Manzur said: 
“Al-Lawh: every wide, flat surface or sheet of wood.
Al-Azhari said: Al-Lawh is a flat surface of wood, and a shoulder-blade [of an animal], if it is written on, may be called a lawh.”
Al-Lawh is something that is written on.
Al-Lawh: al-Lawh al-Mahfuz , as in the verse (interpretation of the meaning), (Inscribed) in al-Lawh al-Mahfuz (the Preserved Tablet) [al-Buruj 85:22] means, the place where the decrees of Allah are kept. 
Every wide bone is a lawh.The plural form is alwah.” (Lisan al-Arab, 2/584)
What is al-lawh al-mahfuz?
Ibn Kathir (may Allah have mercy on him) said:
“In ‘al-Lawh al-Mahfuz (the Preserved Tablet)’ means, it is among the higher group (i.e., angels), preserved and protected from anything being added or taken away, or any alteration or changes.” (Tafsir Ibn Kathir, 4/497, 498)
Ibn al-Qayyim (may Allah have mercy on him) said:
“Preserved: most readers recite this with a kasrah, i.e., it is a description of the Lawh. This indicates that the shayatin are not able to bring it down, because its location is protected and they cannot reach it. And it is itself protected, so the Shaytan cannot add anything to it or take anything away from it.
Allah, may He be glorified, has described it as protected or guarded in the verse (interpretation of the meaning):
Verily, We, it is We Who have sent down the Dhikr (i.e. the Quran) and surely, We will guard it (from corruption). [al-Hijr 15:9]. And its location is also described as being guarded in this surah.
Allah, may He be glorified, is protecting its location, and protecting it from having anything added or taken away, or being distorted. He is protecting its meanings from being twisted, just as He is protecting its words from being changed, and He is protecting its letters so that nothing is added or taken away.” (al-Tabyan fi Aqsam al-Quran, p. 62).
Is al-Lawh al-Mahfuz on the forehead of Israfil?
As for the reports in some books of Tafsir that al-Lawh al-Mahfuz is on the forehead of Israfil or that it was created of green chrysolite, etc., none of these reports have been proven. It is part of the Unseen (al-ghayb) of which we cannot accept any reports except from the one who received Revelation concerning it.
For more, please see these answers: 112107 and 316842 . 
And Allah knows best.