Madonna has bought Britney Spears a Kabbalah book as an engagement gift.

She presented Spears and fiancé Kevin Federline with one of the Jewish faith's central texts, the Zohar.

The special bound edition is worth thousands of pounds and apparently Spears keeps it with her.

A source told The Sun: "Britney was delighted with the book. She has read it thoroughly and seems completely taken with it.

"Madonna has always looked out for Britney. When Britney was going through a tough time earlier in the year, Madonna used Kabbalah teachings to help her through."

Experts say the Zohar is an extremely tough read and almost impossible to grasp. But Spears claims it paints "a bigger picture than even the Bible".

She says: "It's just so interesting to me because I've never read stuff like this before."