QUR’AN: and Allah has revealed to you the Book and the Wisdom, and He has taught you what you did not know: As pointed out above it gives the reason why they cannot harm the Prophet in any way. Or may be it shows the reason of the full statement, and they do not mislead but their own souls, and they shall not harm you in any way. In any case, this revelation of the Book and this teaching of the Wisdom is the reason why their attempts to mislead the Prophet (s.a.w.) can never succeed. This is the foundation of his al- ‘ismah (sinlessness, infallibility).
The verse apparently shows that the basic factor from which al-‘ismah emanates is a sort of knowledge which prevents the knower from indulging in sin and mistake. In other words, knowledge prevents one from going astray. Likewise, all good characteristics, like bravery chastity and generosity are the forms of knowledge which are deep rooted in psyche and create their effects and at the same time prevent one from indulging in their opposites like cowardice or rashness, lack of desire or greed, miserliness or extravagance.
Although beneficial knowledge and perfect sagacity keep one clean and prevent his falling in quagmire of depravity or being soiled with filth of sins, (as we see in the people who have knowledge and wisdom, and steeped in piety and religion). However, it is such a cause as brings its effects most of the times but not always. The same is the case with all material and natural causes which are found in the universe. Look at anyone who is perfect in any field; you will find that his perfection does not protect him from mistake always and without any fail. It is a common trait of all causes which we see and observe.
The reason is that man possesses various powers of consciousness and at times some of them push the others to the back of the mind and man becomes oblivious of those factors. A man with faculty of piety will not be inclined to follow base desires as long as he is conscious of the virtue of his piety; but a time may come when the fire of desire is inflamed and he being tempted by that desire becomes oblivious of the virtue of piety or his consciousness of piety becomes weak, and he commits what piety would never tolerate and indulges in base desires. The same is the case with all conscious causes found in man. Otherwise, man will never deviate from the effects of any of these causes as long as the cause remains intact. In short, whenever man goes against the dictates of virtue, it happens when some causes overpower the others and man forgets the dictates of virtue. But as for this faculty which is called the power of al-‘ismah it is a conscious cause emanating from knowledge which can never be overpowered. Had it been like other consciousness and comprehensions, it could have sometimes failed and deviated from the right path. This knowledge is not like other knowledge and comprehensions which we are familiar with and which can be acquired and learned from teachers.
Allah has pointed to this unique knowledge in this talk addressed particularly to His Prophet (s.a.w.) when he says: and Allah has revealed to you the Book and the Wisdom and He has taught you what you did not know. It is an exclusive talk which we cannot properly understand because we have not tasted this type of knowledge and consciousness. However, if we look at some of the Divine speeches -for example: Say: "Whoever is the enemy of Jibril – for surely he brought it down to your heart by Allah’s command…" (2:97). The faithful spirit has descended with it upon your heart that you may be of the warners in plain Arabic language (26:193-5) – we will clearly see that this sending down of the Book is rooted in knowledge. Some other verses show that this sending down of the Book refers to revelation and talking as may be seen in the following verses: He has made plain to you of the religion what He enjoined upon Nuh and that which We have revealed to you and that We enjoined upon Ibrahim and Musa and’Isa… (42: 1 3); Surely, We have revealed to you as We revealed to Nuh and the prophets after him… (4:163); "… / do not follow aught save that which is revealed tome…" (6:50); "… I only follow what is revealed to me from my Lord…" (7:203).
It is inferred from these various verses that al-inzal (sending down) means revelation of the Book and the Wisdom – and it is a sort of divine teaching to the Prophet (s.a.w.). Nevertheless, the teaching referred to by the words: and He has taught you what you did not know, is something quite different from the teaching through revelation of the Book and the Wisdom; the verses deal with the judicial decisions of the Prophet (s.a.w.) in various events and in the litigations which are brought to him for judgment, and that judgment is given by his own opinion. It has nothing to do with the Book and the Wisdom – although it depends on them – it is the result of his own view and opinion.
It appears from the above that the sending down and the teaching in the words: and Allah has sent down to you the Book and Wisdom and He has taught you what you did not know, refer to two categories of knowledge: one, teaching through revelation and sending of the faithful spirit to the Prophet (s.a.w.); two, teaching through inspiration created in the heart and the secret divine thought without the agency of any angel. This is what is supported by the traditions which have come to us about the prophetic knowledge. Therefore, the sentence: and He has taught you what you did not know, means: Allah has given you a particular knowledge which you could never get through the normal means which help man in learning acquired knowledge; that particular knowledge is given only by Allah to His chosen ones.
Clearly, this Divine gift which we call al-‘is,mah is a sort of knowledge and consciousness which is totally different from all other types of knowledge inasmuch as this knowledge is never overpowered by any other faculty; rather it overpowers all other faculties and uses them according to its own wisdom. In this way, it fully protects the holder of al-‘ismah from going astray and committing mistakes. It has come in the traditions that the Prophet and the Imams do have a spirit which is called the Holy Spirit; and it supports them and protects them from sin and mistake. It is this Spirit which is mentioned in the verse: And thus did We reveal to you a Spirit by Our command. You did not know what the Book was nor (what) the faith (was), but We made it a light guiding thereby whom We please of Our servants (42:52). (This meaning may be inferred if we take the apparent meaning of the verse that a guiding Spirit was sent to the Prophet, s.a.w.). Similarly, there is the verse: And We made them Imams who guided (people) by Our command and We revealed to them the doing of good and the keeping up of the prayer and the giving of the alms and Us (alone) did they worship (21:73). We shall explain in its place the meaning of this verse, God willing, that it refers to the support given by the Holy Spirit to the Imams for doing good and worshipping Allah.
The above explanations also show that the Book mentioned in the verse: and Allah has revealed to you the Book and the Wisdom and has taught you what you did not know, refers to the revelations sent for removing the peoples’ conflicts; as was mentioned in the verse: Mankind was but one people; so Allah sent the prophets as bearers of good tidings and as warners, and He sent down with them the book with the truth, so that it might judge between the people in that in which they differed… (2:213), as was explained in the second volume of this book.
The wisdom mentioned in the verse refers to all Divine cognition sent through revelation which were beneficial for this world and the hereafter. The sentence: and He has taught you what you did not know, refers to something totally different from general cognition obtained from the Book and the Wisdom.
The above explanations show the shortcomings of some exegetes regarding exegesis of this verse. Some have taken the Book as the Qur’an and the Wisdom as the commandments found in it and have said that: what you did not know refers to the shari’ah and the knowledge of the unseen. Others have explained the Book and the Wisdom as the Qur’an and the sunnah and what you did not know as the shari’ah and the stories of the previous prophets and other such information. There are other such explanations; but what we have written in the explanation shows how weak such other explanations are.
 4:113; this popular discourse is taken from the english translation of the book ‘Tafseer Al Mizan’, by the late Allamah Tabataba’i (qs), available here.