1.Rayb means doubt........!! That is Book in which there is no Rayb, guidance for the Muttaqin........!!
2.Hidayah - correct guidance - is only granted to those who have Taqwa - fear of Allah.
3.It is for those who believe, a guide and a healing.
4.And as for those who disbelieve, there is heaviness (deafness) in their ears, and it (the Qur'an) is blindness for them. They are those who are called from a place far away (so they neither listen nor understand)
5. And We send down of the Qur'an that which is a healing and a mercy to those who believe (in Islamic Monotheism and act on it), and it increases the Zalimin (wrongdoers) in nothing but loss)
6.(O mankind! There has come to you a good advice from your Lord (i. e. the Qur'an, enjoining all that is good and forbidding all that is evil), and a healing for that (disease of ignorance, doubt, hypocrisy and differences) which is in your breasts, ـ a guidance and a mercy (explaining lawful and unlawful things) for the believers)