The Arabic word FURQAN ( Arabic: فرقان) is the criterion or the standard to distinguish between good and bad. The name “The Criterion” refers to the Qur’an itself as the decisive(Key) factor between the Good and the Evil. The 25th Surah of the Qur’an is also named as ‘Al-Furqan’ which means Criterion and it has 77 aayaath.
According to Dr. Sobhy as-Salih, this word is also not Arabic but Aramaic, the original language in which Gospel/ Injeel was revealed in.
From the language the word Furqaan describes something which separates a thing into different parts. In the above ayath Allah used the word Faraqnaa in describing how He separated the water of the sea into two parts so as to allow Moses(Musa) and his followers to cross the dry path.
Verily, those who divide[Farraqo (break up)] their religion and break up into sects (all kinds of religious sects), you (O Muhammad) have no concern in them in the least. Their affair is only with Allah..QuranSurah Anam 6:159
Similarly Allah uses the word Farraqo to describe the evil act of breaking up the religion into separate sects. So again the word is used in reference to that which separates something into parts.
The Furqaan means the Criterion which separates the truth (Haqq) from falsehood (Baatil) and through it Allah made the truth known to mankind.
The month of Ramadhan [is that] in which was revealed the Qur’an, a guidance for the people and clear proofs of guidance and criterion. QuranSurah Baqarah2:185
In the above ayath Allah mentions an important attribute of the Quran which we should all be familiar with, and that is its description of being the Furqan. This is an important characteristic, for the word Quran describes the attribute of how The Book of Allah is recited whereas the word Furqan describes the criterion whereby truth is separated from falsehood. And when Faraqnaa (We separated) the sea for you and saved you, and drowned the people of Pharaoh while you were watching.QuranSurah Baqarah 2:50
Allah refers to His scriptures as the Furqan: The month of Ramadhan [is that] in which was revealed the Qur'an, a guidance for the people and clear proofs of guidance and criterion (Furqan). QuranSurah Baqarah2:185
Blessed is He Who sent down The Furqaan to His slave so that it may be a warning to the Aalameen. QuranSurah Furqan 25:1
Similarly Allah describes the Quran as the Furqaan given to His slave Prophet Muhammad ﷺwhereby the people were once again brought out from darkness into light with truth made distinct from falsehood; guidance made clear from misguidance; and the Halaal made known from the Haraam.
In addition Allah uses the word Furqaan specifically when describing His Books which He sent as guidance from Him. Through these divine scriptures the children of Adam where able to distinguish truth from falsehood; guidance from misguidance; and the permissible from the prohibited. It is also important to note that the Furqaan was given to Prophets, so it was impossible to understand the scriptures with all their beliefs and laws without understanding the explanation and implementation offered by the Prophets of Allah.
And (remember) when We gave Musa (Moses) the Scripture [the Taurat (Torah)] and the criterion (of right and wrong) so that you may be guided aright. QuranSurah Baqarah2:53
In the above ayath Allah describes the Torah as the Furqaan but He also mentions how He gave the Furqaan to Moses so that guidance could reach the people. Surely We have sent down to you The Book in truth that you may judge between mankind with that which Allah has shown you. Quran Surah Nisa 4:105
Prophet Muhammadﷺjudged between the people using the Furqaan in the manner Allah had shown him through the Hikmah and Sunnah bestowed to him. So he clarified truth from falsehood, guidance from misguidance, and halal from haraam by explaining the aayaath in the Book of Allah through his Sunnah.