He repents then he goes back to sin

Allah has created us for a great purpose, which is to worship Him alone with no partner or associate. Allah says (interpretation of the meaning): 

“And I (Allah) created not the jinn and mankind except that they should worship Me (Alone)” [al-Dhaariyaat 51:56]

Every Muslim must strive to worship His Lord as much as He can. 

“Allah burdens not a person beyond his scope”

[al-Baqarah 2:286 – interpretation of the meaning]

But man is weak and surrounded by enemies on all sides, and his own self urges him to do evil, and the Shaytaan flows through him like blood, and he lives in this world which is attractive to him… so how can he be safe from these enemies unless Allah has mercy on him? 

However, Hell is surrounded with whims and desires, and Paradise is surrounded with difficulties. So each person must turn to Allah and ask Him to help him to remember Him and be grateful to Him and to worship Him properly. Abu Bakr came to the Prophet (peace and blessings of Allah be upon him) and said to him, “Teach me a du’aa’ that I can say in my prayer.” He said, “Say Allahumma inni zalamtu nafsi zulman katheeran wa laa yaghfir al-dhunooba illa anta faghfir li maghfiratan min ‘indika warhamni innaka anta al-Ghafoor al-Raheem (O Allah, I have done great injustice to myself and no one forgives sin except You. Grant me forgiveness from You and have mercy on me, for You are the Oft-Forgiving, Most Merciful).” (Narrated by al-Bukhari, 834; Muslim, 2705). 

Think about this hadeeth, how the Prophet (peace and blessings of Allah be upon him) taught Abu Bakr (may Allah be pleased with him), who is the best of this ummah after the Prophet (peace and blessings of Allah be upon him), to say, “O Allah, I have done great injustice to myself.” If Abu Bakr was to say this – when he was the best of the people – then what should we say?! O Allah, bestow Your mercy upon us. 

There was another Sahaabi – one of the best and most knowledgeable of the Sahaabah – to whom the Prophet (peace and blessings of Allah be upon him) said, “I love you, O Mu’aadh.” (Mu’aadh said), “And I love you, O Messenger of Allah.” The Messenger of Allah (peace and blessings of Allah be upon him) said: “Do not forget to say in every prayer, ‘Rabbi a’inni ‘ala dhikrika wa shukrika wa husni ‘ibaadatika (O Allah, help me to remember You, thank You and worship You properly.).’” (al-Nasaa’i, 1303; classed as saheeh by al-Albaani in Saheeh al-Nasaa’i, 1236). 

Look at this advice that the Prophet (peace and blessings of Allah be upon him) gave to one of those whom he loved the most, how he told he to ask Allah to help to worship Him, for if a person is deprived of such help from Allah then he is indeed deprived. 

So we must turn to Allah and ask Him to help us to do that which He has enjoined upon us. 

Because all human beings are bound to fall short, Allah has commanded us to repent from all sins. Allah says (interpretation of the meaning): 

“And all of you beg Allah to forgive you all, O believers, that you may be successful” [al-Noor 24:31]

“Seek the forgiveness of your Lord, and turn to Him in repentance” [Hood 11:3]

“O you who believe! Turn to Allah with sincere repentance! It may be that your Lord will expiate from you your sins, and admit you into Gardens under which rivers flow (Paradise)” [al-Tahreem 66:8]

“In these verses, Allah links expiation of sin and admission to Paradise to sincere repentance, which includes giving up sin and avoiding it, regretting what has happened in the past and sincere resolve never to return to it out of fear and respect for Allah, hoping for His reward and fearing His punishment.” 

(Shaykh ‘Abd al-‘Azeez ibn Baaz, in Majmoo’ al-Fataawa – al-‘Aqeedah, part 2, p. 640). 

It was narrated that Abu Hurayrah (may Allah be pleased with him) said: “I heard the Messenger of Allah (peace and blessings of Allah be upon him) say, ‘By Allah, I ask the forgiveness of Allah and repent to Him more than seventy times each day.’” (Narrated by al-Bukhari, 6307). 

It was narrated that Abu Burda said: “I heard al-Agharr, who was one of the Companions of the Prophet (peace and blessings of Allah be upon him) say, ‘The Messenger of Allah (peace and blessings of Allah be upon him) said, “O people, repent to Allah, for I repent to Him one hundred times each day.”’” (Narrated by Muslim, 2702). 

These reports encourage us to repent to Allah. The leader of those who repent – the Messenger of Allah (peace and blessings of Allah be upon him) – repented to Allah one hundred times each day, so it is more essential for us to repent a great deal, because of our many sins. There is no power and no strength except with Allah. 

With regard to your saying that you repent and then go back to sin, then you repent and then go back to sin, we say to you that even if you go back to sin time and time again, you should repent a great deal and annoy your Shaytaan who is laying in wait for you. Remember that Allah “spreads out His hand at night to accept the repentance of those who sinned during the day, and He spreads out His hand during the day to accept the repentance of those who sinned during the night, (and this will continue) until the sun rises from the west.” (Narrated by Muslim, 2759) 

The gate of repentance is open. Abu Hurayrah said: “The Messenger of Allah (peace and blessings of Allah be upon him) said: ‘Whoever repents before the sun rises from the west, Allah will accept his repentance.’” (Narrated by Muslim, 2703). 

And the Prophet (peace and blessings of Allah be upon him) said: “Allah will accept the repentance of His slave so long as the death rattle has not yet reached his throat.” (Narrated by al-Tirmidhi and classed as hasan by al-Albaani in Saheeh al-Tirmidhi, 2802). 

But you should note that there are conditions for repentance which must be met if it is to be acceptable according to sharee’ah. These conditions are explained in detail in the answer to question no. 13990. Please see also question no. 5092. 

Finally we advise you to strive against your self which urges you to do evil, and to seek refuge with Allah from its evil and the evil of the accursed Shaytaan. The Prophet (peace and blessings of Allah be upon him) used to seek refuge with Allah from the evil of his own self and from the evil and snares of the Shaytaan, as it says in the hadeeth: “A’oodhu bika min sharri nafsi wa sharri’l-shaytaan wa sharakihi (I seek refuge with You from the evil of my own self and from the evil of the Shaytaan and his snares).” 

You should also keep away from the means of sin; Allah has warned us against approaching zina, as He says (interpretation of the meaning): 

“And come not near to unlawful sex” [al-Isra’ 17:32]

That is done by keeping away from the things that lead to zina. 

Keep on beseeching Allah and making du’aa’ asking Him to give you strength, expiate your sins and bless you with taqwa (piety). 

We ask Allah to bless us all with sincere repentance. Praise be to Allah, the Lord of the Worlds.