What is the meaning of the term "confirming what came before it" in the Holy Qur'an, and does it refer to the Gospel that was in the hands of the Christians at the time of the Qur'an's revelation, or the one revealed to Jesus, peace be upon him?

Allah Almighty says: ﴿And We have sent down to you the Book in truth, confirming what was before it of the Scripture and a guardian over it.﴾ (Al-Ma'idah/48). The "Book" here refers to the Qur'an, which confirms the scriptures that preceded it and is a guardian and judge over them. The pronoun in "it" refers to the Qur'an, meaning "what was before it." The Qur'an's confirmation of the previously revealed scriptures is mentioned in other parts of the Qur'an. This confirmation pertains to correct matters such as the worship of Allah and the following of His messengers, not to what the People of the Book distorted of falsehood and polytheism. The exegetes confirm that the Qur'an confirms the truth found in the previous scriptures and nullifies the falsehood and distortions within them.