The Book, is the Qur'an, and Rayb means doubt. As-Suddi said that Abu Malik and Abu Salih narrated from Ibn `Abbas, and Murrah Al-Hamadani narrated from Ibn Mas`ud and several other Companions of the Messenger of Allah ﷺ that,
لاَ رَيْبَ فِيهِ
(In which there is no Rayb), means about which there is no doubt. Abu Ad-Darda', Ibn `Abbas, Mujahid, Sa`id bin Jubayr, Abu Malik, Nafi` `Ata', Abu Al-`Aliyah, Ar-Rabi` bin Anas, Muqatil bin Hayyan, As-Suddi, Qatadah and Isma`il bin Abi Khalid said similarly. In addition, Ibn Abi Hatim said, "I do not know of any disagreement over this explanation." The meaning of this is that the Book, the Qur'an, is without a doubt revealed from Allah. Similarly, Allah said in Surat As- Sajdah,
الم - ذَلِكَ الْكِتَابُ لاَ رَيْبَ فِيهِ هُدًى لِّلْمُتَّقِينَ
(Alif Lam Mim). The revelation of the Book (this Qur'an) in which there is no doubt, is from the Lord of all that exists) (2:1-2).
Some scholars stated that this Ayah - 2:2 - contains a prohibition meaning, "Do not doubt the Qur'an." Furthermore, some of the reciters of the Qur'an pause upon reading,
لاَ رَيْبَ
(there is no doubt) and they then continue;
فِيهِ هُدًى لِّلْمُتَّقِينَ
(in which there is guidance for the Muttaqin (the pious and righteous persons)). However, it is better to pause at,
لاَ رَيْبَ فِيهِ
(in which there is no doubt) because in this case,
هُدًى
(guidance) becomes an attribute of the Qur'an and carries a better meaning than,
فِيهِ هُدًى
(in which there is guidance).
Hidayah - correct guidance - is only granted to those who have Taqwa - fear of Allah. Allah said,
قُلْ هُوَ لِلَّذِينَ ءَامَنُواْ هُدًى وَشِفَآءٌ وَالَّذِينَ لاَ يُؤْمِنُونَ فِى ءَاذَانِهِمْ وَقْرٌ وَهُوَ عَلَيْهِمْ عَمًى أُوْلَـئِكَ يُنَادَوْنَ مِن مَّكَانٍ بَعِيدٍ
(Say: It is for those who believe, a guide and a healing. 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)) (41:44), and,
وَنُنَزِّلُ مِنَ الْقُرْءَانِ مَا هُوَ شِفَآءٌ وَرَحْمَةٌ لِّلْمُؤْمِنِينَ وَلاَ يَزِيدُ الظَّـلِمِينَ إَلاَّ خَسَارًا
(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) (17:82).
This is a sample of the numerous Ayat indicating that the believers, in particular, benefit from the Qur'an. That is because the Qur'an is itself a form of guidance, but the guidance in it is only granted to the righteous, just as Allah said,
يَأَيُّهَا النَّاسُ قَدْ جَآءَتْكُمْ مَّوْعِظَةٌ مَّن رَّبِّكُمْ وَشِفَآءٌ لِّمَا فِى الصُّدُورِ وَهُدًى وَرَحْمَةٌ لِّلْمُؤْمِنِينَ
(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) (10:57).
Ibn `Abbas and Ibn Mas`ud and other Companions of the Messenger of Allah ﷺ said,
هُدًى لِّلْمُتَّقِينَ
(guidance for the Muttaqin (the pious and righteous persons), means, a light for those who have Taqwa.
Ibn `Abbas said about,
هُدًى لِّلْمُتَّقِينَ
(guidance for the Muttaqin) that it means, "They are the believers who avoid Shirk with Allah and who work in His obedience." Ibn `Abbas also said that Al-Muttaqin means, "Those who fear Allah's punishment, which would result if they abandoned the true guidance that they recognize and know. They also hope in Allah's mercy by believing in what He revealed." Further, Qatadah said that,
لِّلْمُتَّقِينَ
(Al-Muttaqin), are those whom Allah has described in His statement;
الَّذِينَ يُؤْمِنُونَ بِالْغَيْبِ وَيُقِيمُونَ الصَّلٰوةَ
(Who believe in the Ghayb and perform the Salah) (2:3), and the following Ayat. Ibn Jarir stated that the Ayah (2:2) includes all of these meanings that the scholars have mentioned, and this is the correct view. Also, At-Tirmidhi and Ibn Majah narrated that `Atiyah As-Sa`di said that the Messenger of Allah ﷺ said,
«لَا يَبْلُغُ الْعَبْدُ أَنْ يَكُونَ مِنَ الْمُتَّقِينَ حَتَّى يَدَعَ مَالَا بَأْسَ بِهِ حَذَرًا مِمَّا بِهِ بَأْس»
(The servant will not acquire the status of the Muttaqin until he abandons what is harmless out of fear of falling into that which is harmful.) At-Tirmidhi then said "Hasan Gharib."
Huda here means the faith that resides in the heart, and only Allah is able to create it in the heart of the servants. Allah said,
إِنَّكَ لاَ تَهْدِى مَنْ أَحْبَبْتَ
(Verily, you (O Muhammad ) guide not whom you like) (28:56),
لَّيْسَ عَلَيْكَ هُدَاهُمْ
(Not upon you (Muhammad ) is their guidance) (2:272),
مَن يُضْلِلِ اللَّهُ فَلاَ هَادِيَ لَهُ
(Whomsoever Allah sends astray, none can guide him) (7:186), and,
مَن يَهْدِ اللَّهُ فَهُوَ الْمُهْتَدِ وَمَن يُضْلِلْ فَلَن تَجِدَ لَهُ وَلِيًّا مُّرْشِدًا
(He whom Allah guides, he is the rightly guided; but he whom He sends astray, for him you will find no Wali (guiding friend) to lead him (to the right path)) (18:17).
Huda also means to explain the truth, give direction and lead to it. Allah, the Exalted, said,
وَإِنَّكَ لَتَهْدِى إِلَى صِرَٰطٍ مُّسْتَقِيمٍ
(And verily, you (O Muhammad ) are indeed guiding (mankind) to the straight path (i.e. Allah's religion of Islamic Monotheism)) (42: 52),
إِنَّمَآ أَنتَ مُنذِرٌ وَلِكُلِّ قَوْمٍ هَادٍ
(You are only a warner, and to every people there is a guide) (13:7), and,
وَأَمَّا ثَمُودُ فَهَدَيْنَٰـهُمْ فَاسْتَحَبُّواْ الْعَمَى عَلَى الْهُدَى
(And as for Thamud, We showed and made clear to them the path of truth (Islamic Monotheism) through Our Messenger (i.e. showed them the way of success), but they preferred blindness to guidance) (41:17).
testifying to this meaning.
Also, Allah said,
وَهَدَيْنَٰـهُ النَّجْدَينِ
(And shown him the two ways (good and evil).) (90:10)
This is the view of the scholars who said that the two ways refer to the paths of righteousness and evil, which is also the correct explanation. And Allah knows best.
The root meaning of Taqwa is to avoid what one dislikes. It was reported that `Umar bin Al-Khattab asked Ubayy bin Ka`b about Taqwa. Ubayy said, "Have you ever walked on a path that has thorns on it" `Umar said, "Yes." Ubayy said, "What did you do then" He said, "I rolled up my sleeves and struggled." Ubayy said, "That is Taqwa."