I'd like to know the meaning of the Surah 3:7.What are the "basic's of the Book"(Umm al-kitab) and "and others are not of well- established meaning".

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

Allaah says (what means): {It is He who has sent down to you, [O Muhammad sallallaahu ‘'alayhi wa sallam], the Book; in it are verses [that are] precise-they are the foundation of the Book-and others unspecific. As for those in whose hearts is deviation [from truth], they will follow that of it which is unspecific, seeking discord and seeking an interpretation [suitable to them]. And no one knows its [true] interpretation except Allaah. But those firm in knowledge say,” We believe in it. All [of it] is from our Lord.” And no one will be reminded except those of understanding.} [Quran 3:7]

Allaah informs us in the above verse that the Quran contains verses that are entirely clear.

The verses of the Quran that are clear are those the interpretation and meaning of which are clear and understood. This means that they are clear and easy to understand for every person. The saying of Allaah: "These are the foundation of the Book" meaning that people refer to these clear verses when they have doubt about something."

The verses that are not very clear are verses that many or some people doubt about the understanding of their meaning and interpretation.

So, their meaning could respond to the clear verses, or could refer to something else depending on their form and structure. It is also said that the verses that are not clear, are the verses that only Allaah knows their meaning.

Imaam Al-Qurtubi said: "The verses that are not clear are the verses that nobody knows the meaning of, and it is only Allaah who knows their meaning. Some of the scholars said: "Like the time of the Hour, the appearance of Gog and Maggog, the the appearance of the Dajjal, the ascendence of 'Eesa, and the interrupted letters which are at the beginning of some Chapters of the Quran. I (i.e. Al-Qurtubi) say: "This is the best thing which was said about the verses that are not clear."

Then Allaah informed us about the people in whose hearts there is a deviation from the truth, that they follow that which is not clear as to falsify its meaning and distort it in order to serve their wrong purposes.

Allaah Knows best.