What is Injeel (Gospel) according to Al Quran 3:3-4?

Understanding the term Injeel (Gospel) in the Quran

​Allah ﷻ says in the Quran: "Step by step has He bestowed upon you from on high this divine writing, setting forth the truth which confirms whatever there still remains [of earlier revelations]: for it is He who has bestowed from on high the Torah and the Injeel (Gospel) aforetime, as a guidance to mankind, and it is He who has bestowed [upon man] the Furqan (standard by which to discern the true from the false i.e. Quran)." Asad Translation[1]

The key to know which Injeel is being referred above we need to understand the term "ma bayna yadayhi" which is translated in the above Asad's translation, quite differently from usual English translations. The usual one's translate it as "confirming what was before it" while Asad’s translation gives it much clearer meaning and translates it as "whatever there still remains [of earlier revelations]". Since ma bayna yadayhi can be understood as "whatever there still remains [of earlier revelations]" we may understand that Allah ﷻ is reminding us that the present day Injeel and Torah are not in their original form. This explanation of ma bayna yadayhi as "whatever there still remains [of earlier revelations]" is further strengthened by the fact that in verse 4 Allah ﷻ does not refer to the Quran as Quran, He calls it Furqan which means "standard by which to discern the true from the false". This teaches us that if Allah ﷻ accepted the present day Injeel and Torah in its original form, then He would not have used the term Furqan in the above context. In simple words Asad’s translation proves for us that Allah ﷻ  is making 2 points very clear in Al Quran 3:3–4:

1. Firstly that Injeel and Torah are not in their original form therefore it would be premature to say that Allah ﷻ is limiting the meaning of the term Injeel to 4 present day Gospels (Mark, Mathew, John & Luke), written much later after Isa ibn Maryam (alaihi salaam). Since that is a historical fact, hence it makes sense for us that that the term Gospel frequently mentioned in the Quran is not identical with what is known today as the Four Gospels, but refers to an original, since lost, revelation revealed to Isa ibn Maryam (alaihi salaam) and known to his contemporaries under its Greek name of Evangelion ("Good Tiding"), on which the Arabicized form Injeel is based.
2. Secondly Allah ﷻ  refers to the Quran with the term Furqan (standard by which to discern the true from the false) to stress the first point that only this book has the ability to now truly confirm "whatever there still remains (of earlier revelations i.e. Torah & Injeel)"
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Whats clarifies for us and strengthens this view point even further is the fact that there are still discernible truths mentioned in whatever is remaining of the Injeel and Torah which Quran or Furqan clearly confirms such as the divinity of One God, the temple in Jerusalem, the exodus, the miraculous birth of Isa ibn Maryam (alaihi salaam), Moses (alaihi salaam) preaching to Pharoah, his brother Aaron (alaihi salaam), important incidents related to Abraham (alaihi salaam) and Noah (alaihi salaam), the tempting of satan to Adam and Even (alaihim us salaam) etc. All these events are confirmed by the Furqan (Quran) yet at the same time separating the truth from falsehood in those events which unfortunately has been crept in to them such as blaming Eve for Adam’s sin, cursing the black nations through cursing Noah's elder son Ham, Aaron worshiping calf with Children of Israel, the concept of trinity, Children of Israel defacto status of God’s chosen people, Prophet Lot (alaihi salaam) committing adultery with his daughters and all types of nonsense that has crept in to those authentic accounts and corrupted them. The only way to purify the corruption affecting these accounts in Bible is to refer to the Quran and see if it confirms, rejects or remains silent. If it confirms, we accept, if it rejects, we reject and if Quran remains silent then we say "Allah ﷻ knows best."

References:
[1] Al Quran 3:3–4