Man is an addressee concerning jurisprudence, while his diverse activities are fields in which Islamic laws and legislation are practised. And Islam did not come but to coincide between man's activities with his dimensions in life, between the will of good and the will of mercy in this existence. Therefore, this conformity needs utmost accuracy in evaluating man's nature and his readiness and capabilities lest this conformity becomes impracticable, and demolishes the goal of the religion.
Hence, the Islamic duties are obligatory according to the human's readiness and ability.
The Almighty, Allah says:
﴾Allah does not impose upon any soul a duty but to the extent of its ability;...﴿ Holy Qur'an (2:286)
﴾O you who believe! follow you not the steps of Satan; for whoever follows the steps of Satan, he (Satan) enjoines (unto him) filth and evil; and were it not for Allah's grace on you and H is mercy, not One of you would have ever been pure, but Allah purifies whom He wills; and Allah is All-Hearing, All-Knowing.﴿ Holy Qur'an (24:21)
﴾Have you not considered those who claim themselves pure? No, Allah purifies whom He will; and they will not be wronged the skin of a date-stone.﴿ Holy Qur'an (4:49)
﴾And I exculpate not myself; surely (one's) self is wont to bid (him to) evil, except those on whom my Lord has mercy. Surely my Lord is Oft-Forgiving, All-Merciful.﴿ Holy Qur'an (12:53)
﴾And certainly We created man, and We know what his mind suggests to him and We are nearer to him than h is life-vein.﴿ Holy Qur'an (50:16)
﴾Verily Allah loves, among His servants, those who turn towards Him when they are tempted.﴿7
﴾Certainly Allah, the Almighty gave three qualities to those who repent,. if one of these qualities are given to all people of the heavens and the earth, they surely would be saved; the Most High8 says: 'Surely Allah loves those who turn too much (to Him)﴿ (Holy Qur'an: (2:222)' and
﴾Those who bear the Throne of Power and those around it celebrate the praise of their Lord and believe in Him and ask protection for those who believe: Our Lord, You embrace all things in mercy and knowledge, so protect those who turn (to You)- till He says-. surely you are the Mighty, the Wise.﴿ Holy Qur'an (40:7-9)
﴾And those who call not with Allah upon any other god, slay not a soul which Allah has forbidden except for just cause, and do not commit fornication; for whoever does these shall receive (the recompense) of the sin. For him the punishment shall be doubled on the Resurrection Day, and therein he shall abide forever, disgraced. Except him who repents and believes and does righteous deeds, for these are they of whom Allah changes their evil deeds into good deeds. And Allah is All-Forgiving, All-Merciful.﴿ Holy Qur'an (25:68-70)
On the one hand, Islam aims at the process of conformity between man's will and his activity; on the other hand, between the divine will of good and mercy. It takes into consideration that the human ability, includes his psychological inclinations and limited bodily and mental ability and what he suffers of the division between the two ways in life; the way of good and evil, cannot always harmonize with the will of Allah, the Exalted, nor can he stand erect along a straight line without any regression or transgression and deviation because the nature of what he bears of capabilities, motives, and tendencies, is unable to be the true shadow on this land for the ultimate will of good and the greatness of mankind.
Concerning this concept, Imam Ja'far as-Sadiq (a.s.) says:
"A believer looks like an ear (of wheat) which sometime rises straight up and sometimes inclines to itself."
It is inevitable for a believer to make mistakes now and then."
Therefore, Islam, as it legislates laws, regulations, and the rules of essential regularities for life, also takes into consideration the fact that there is not a perfect application and the occurrence of offense and deviation from righteousness exists, so it made, for this deviation and disobedience, a special solution and a comprehensive legislation for organizing it in order man return to the path of righteousness and coincide with the will of good and the great goal of this existence which is an integrative trend towards the public interest.
Accordingly, the Islamic legislation for repentance came to emphasize that man cannot be a volitional essence representing the wilt of good and ascend the ladders of perfectness without Allah's mercy and His opening the door of returning towards Him whenever he deviates or goes stray. So, Islam is realistic and practical when it deals with man in a way which fits his true nature as a human who makes mistakes and. then goes straight or deviates (from the right path) and then follows the right way.
Therefore both the Holy Qur'an and the noble Prophetic traditions emphasized this fact, for man, in order to remind him about Allah's grace for him and also to recognize why does he commits sin? Why does he repent? And what is his relationship with Allah when he disobeys, and then repents; deviates and then asks for forgiveness.
Consequently the following text explains and discovers for man, his true nature, his relationship and the degree of his harmony
with the will of Allah, the Almighty:
﴾...and wen it not for Allah's grace upon you and H is mercy, not one of you would have ever been pure...﴿ Holy Qur'an (24:21)
﴾Have you not considered those who claim themselves pure? No, Allah purifies whom He wills; and they will not be wronged the skin of a date-stone.﴿ Holy Qur'an (4:49)
﴾And I call not myself sinless; surely (man's) self is wont to command evil, except those on whom my Lord has mercy. Surely my Lord is Forgiving, Merciful.﴿ Holy Qur'an (12:53)
﴾And certainly We created man, and We know what his mind suggests to him and We are nearer to him than his life-vein.﴿ Holy Qur'an (50:16)
These verses declare that the human self is wont to command evil and, also, inclines to be independent in this existence and to be separated from Allah's will since it succumbs to illusions, devilish insinuations and Satanic temptations in order to be a god on this land, but it is Allah's mercy which overshadows this miserable creature and overwhelms it by Divine love and forgiveness so that it may raise, once again, from its suppression and collapse and continue on the way of perfection and love of the good. It awakens, in its depths, the sense of conscience and strives to go beyond the circle of darkness into the world of light and to return towards Allah to achieve its aims in reaching Him, and the everlasting eternity and happiness.
Therefore, the angels glorify and praise Allah and ask forgiveness for him (the repentant) and his Creator, Who counting his disobedience and rebellion will be pleased with his return and love his closeness:
﴾Surely Allah loves those who turn to Him, and loves those who keep themselves pure.﴿ Holy Qur'an (2:222)
﴾Whoever repents of his sins has no sin for the repentant is Allah's friend﴿9
Accordingly, the repentant finds the doors of return lawful and the horizons of repentance wide lest despair overcomes him; hopelessness dominates him and continues in committing sin; and thus says farewell to the life of righteousness without return.