I would like to ask a question about the verse: {And We will turn away their hearts and their eyes just as they refused to believe in it the first time. And We will leave them in their transgression, wandering blindly.} [Quran 6:110] Does this mean that those who intend to do a sin (fornication, for example) and to repent afterwards will not be allowed to repent afterwards because one may not be able to repent due to being overwhelmed by his whims and desires, his regarding sin as permissible, and his persisting in it? He may not be able to do this because his time has come and his soul is taken.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

The meaning of the verse is that whoever confronts the verses [signs, evidence, proofs…] of Allah with denial, stubbornness, and arrogance, then Allah will punish him by diverting him from accepting the truth, and his heart will not benefit him, as Allah says (what means): {And when they deviated, Allah caused their hearts to deviate.} [Quran 61:5]

As-Sa‘di said:

"{And We will turn away their hearts and their eyes just as they refused to believe in it the first time. And We will leave them in their transgression, wandering blindly.} [Quran 6:110]; meaning: We will punish them, if they did not believe the first time the caller came to them and the evidence was established against them, by turning their hearts, and preventing them from faith, and not being enabled to tread the Straight Path. And this is from the justice of Allah and His wisdom with His Servants; they are the ones who transgressed against themselves, and He opened the door for them but they did not enter it, and He showed the way for them but they did not tread it; so if they are then denied success, it is appropriate for their conditions."

As for whoever intends to disobey Allah and then abandons it for the Sake of Allah, then he will be rewarded for that and instead of the sin which he was determined to do [and then abandoned it] a good deed will be written for him, because he abandoned the sin for the Sake of Allah.

The Qudsi hadith reads (that Allah said), "When My slave intends to do a good deed but he actually does not do it, I will record it for him as one good deed; but if he does it, I will write it for him as ten good deeds in his favor. In case he intends to do an evil deed, I will forgive that for him as long as he does not commit it. But if he commits it, I will record it for him as one evil deed only." The Prophet said, "The angels said, 'Our Lord, that slave of Yours intended to commit evil;' and Allah is more Knowing of him; then He (the Lord) said, 'Watch him; if he commits (evil), write it against him as one evil deed, and if he refrains from doing it, write it down for him as one good deed, for he desisted from doing it for My sake.'" [Muslim]

As for whoever intended to do evil while intending to repent after doing it, then he is upon a great danger. It is possible that he would not be enabled to repent and that the devil would gradually mislead him and he will continue and persist in sinning – we seek refuge in Allah from that. Also, his appointed time might precede his repentance, and so he would be prevented from it. Allah says (what means): {And prevention will be placed between them and what they desire, as was done with their kind before.} [Quran 34:54]

So this is a great risk – that a person commits a sin and is determined to commit it while intending to repent after that. But this does not mean that his non-repentance is inevitable, as Allah may bless him with repentance and he actually repents; however, he is upon a great danger in persisting in sin, even if he intends to repent after that.

Allah knows best.