What was in Injil before it was changed according to Islam?

In Islam, the Injil (Gospel) is considered a holy scripture that was revealed to Jesus (Isa) by Allah. The Qur'an acknowledges the Injil as a source of guidance and light, confirming the messages of the Torah that preceded it. For instance, it states, And We caused Jesus, son of Mary, to follow in their footsteps, confirming that which was (revealed) before him in the Torah, and We bestowed on him the Gospel wherein is guidance and a light, confirming that which was (revealed) before it in the Torah - a guidance and an admonition unto those who ward off (evil) 5:46.

Islamic tradition holds that the original Injil contained teachings that aligned with the message of monotheism and the worship of one God, similar to the teachings found in the Torah. It is believed that the Injil included guidance on moral conduct, spiritual teachings, and prophecies about the coming of Muhammad as the final messenger.

However, Islamic teachings assert that over time, the original messages of the Injil were altered and corrupted by later followers. This view is reinforced by comments in Islamic tafsir that highlight how certain rulers and leaders manipulated the scriptures for their own purposes, leading to deviations from the original teachings. For example, Tafsir Ibn Kathir discusses how after Jesus, there were kings who altered the Torah and Gospel, and it describes the emergence of various groups who misinterpreted these scriptures, leading to the introduction of practices not prescribed by Allah.

Thus, while the Injil is regarded as an important text in Islam, it is also viewed as having undergone significant changes that led to the current forms of the Gospels in Christianity, which Muslims believe no longer accurately reflect the original revelations given to Jesus.