Surah 6. Al-An'am

69In the sentence, "I am not a keeper over you," Allah is speaking in the first person on His Prophet's behalf. Just as the second person in the Qur'an denotes different people at different places, so the first person also denotes different beings at different places. As is well known, in some places, the second person is the Holy Prophet or the Believers or the people of the Book, and at other places it is the disbelievers or the mushrikin or the Quraish or the Arabs or the human beings in general, though the Qur'an is meant to be the guidance for all mankind, Likewise at some places, the first person is Allah Himself and at others it is the angel, the bearer of the Revelation, or a group of angels, or the Prophets or the Believers, though, in every case, the Words are of Allah. However, one can determine the real "person" with the help of the context.

The meaning of the sentence. "I am not a keeper over you," is : "My only duty is to present the guidance before you. Then it is for you to open your eyes to see it or to keep your eyes shut like a blind man. It is not my duty to force open the eyes of those, who deliberately keep them shut and to make them see what they do riot see."