Kitab-i-mubin has three meanings: (1) This book presents its teachings and instructions and injunctions plainly; (2) it distinguishes between the Truth and falsehood clearly; and (3) its being a Divine Book is obvious: whoever studies it with open eyes will realize that it has not been composed and forged by the Holy Prophet himself.
That is, the verses themselves are a "guidance" and "good news", because they give guidance and convey good news in a most excellent manner.
That is, "These verses of the Qur'an give guidance and convey the good news of a good end only to those people who possess these two qualities: (1) They should affirm faith, that is, accept the invitation of the Qur'an and the Holy Prophet Muhammad (upon whom be Allah's peace and blessings), believe In one God as their only Deity and Lord, accept the Qur'an' as the Book of Allah, acknowledge the Holy Prophet as a true Prophet and their Leader, and also adopt the belief that after this life there is another life, in which man has to render his full account of deeds and be rewarded or punished accordingly. (2) They should not only profess faith verbally, but should also be inclined to follow and obey the Divine Commands practically, and the first indication of this inclination is that they should establish the Salat and pay the Zakat. The verses of the Qur'an will show the right way of life only to those people who fulfill these two conditions; they will explain to them the difference between the right and the wrong at every stage on the way, protect them against the wrong ways at every turn of the way, and bless them with the satisfaction that whatever be the consequences of following the Right Way in the world, in the Hereafter they will certainly attain the eternal and everlasting success and the good will of Allah only through it. For in order to derive full benefit from the teaching of a teacher, one has first to have faith in him, then accept to be his student, and then work according to his instructions. Similarly, a patient who wants to be benefited by a doctor has first to accept him as a physician, and then follow his instructions with regard to medical dosage, prevention, etc. Then only he can assure the patient of the desired results.
Some people have interpreted the words yu'tun-az-zakat in this verse to mean that they should adopt moral purity. But, wherever in the Qur'an the word ita-i-zakat has occurred along with the word iqamat-i-salat, it means payment of the Zakat, which is the second pillar of Islam after the Salat. Moreover, the Qur'an has used the word tazakka for adopting piety and purity and not ita' which is specifically used for the payment of the Zakat. In fact, what is meant to be impressed here is this: In order to benefit fully by the guidance of the Qur'an, it is imperative that one should adopt the attitude of submission and obedience in practical life as well after the affirmation of the Faith, and the establishment of the Salat and the payment of the Zakat is the first indication that one has actually adopted such an attitude. If there is no such indication, it will become obvious that one is rebellious: he might have acknowledged a ruler as such, but he is not inclined to carry out his commands.
Although belief in the Hereafter is an article of the Faith, and a believer will also believe in it along with believing in Tauhid and the Prophethood, here it has been specially mentioned separately in order to bring out its unique importance. The object is to impress that for those people who do not believe in the Hereafter, it is impossible to follow, even tread, the way taught by the Qur'an. For the people of this way of thinking naturally determine their criterion of good and evil by the results that appear, in this world. For them it is not possible to accept any admonition or guidance which seeks to determine the good and evil by the criterion of the gain and loss in the Hereafter. Such people in the first instance do not at all heed the teachings of the Prophets, but if for some reason, they also get included among the believers, they find it difficult to take even the initial steps on the way of the Faith and Islam because of the lack of faith in the Hereafter. For as soon as they will encounter the first situation where the demands of the worldly gains and the losses of the Hereafter will pull them in opposite directions, they will freely allow themselves to be pulled towards the worldly gains without caring in the least for the losses of the Hereafter, even though they may be making all sons of claims to be the believers.
That is. "This is God's Law of Nature and the natural logic of human psychology that when man thinks that the results of his life's struggle are confined to this world only when he does not believe in the existence of any court where his life's work has to be scrutinized and judged finally for good and evil, and when he does not believe in any life hereafter when he will be requited strictly in accordance with the real worth of his life's deeds, he will inevitably develop in himself a material outlook on life, and every kind of conflict between the Truth and falsehood, good and evil, morality and immorality, will appear utterly meaningless to him. Then, whatever earns him pleasure and enjoyment, material progress and prosperity, power and authority, will be the good for him, no matter it be any philosophy of life, any way of life and any system of morality. He will have no concern for truth and reality. His real ambition will be to win successes and earn adornments only of this worldly life, and their pursuit will lead him astray into every valley. Then, whatever he does with this object in view. will be a thing of beauty for him, and he will regard all those others as foolish, who are not absorbed like him in seeking the world, and doing anything and everything without any moral qualm and inhibition.