Madonna is dedicating her new children's book to her adopted son.The pop superstar - who has written a number of children's stories - is said to be drawing on her experiences with Malawian tot David Banda, who she was granted custody of last October, for her next tale. A source said: "She adores David and wants to honor him by writing a boys adventure with a moral lesson."Madonna, 48, is believed to be keen to make sure the book has a Kabbalahist moral message in line with her beliefs. The faith is an off shoot of Judaism, and the singer and her husband Guy Ritchie are both devout followers. It is not the first time Madonna has written a book inspired by one of her children.The star's first story, 'The English Roses', dealt with peer pressure among girls, and was based on her experiences with her daughter Lourdes.