The word(s) "regret" appears 9 time(s) in 9 verse(s) in Quran in Muhammad Habib Shakir translation.

(1) And those who followed shall say: Had there been for us a return, then we would renounce them as they have renounced us. Thus will Allah show them their deeds to be intense regret to them, and they shall not come forth from the fire.

(2) O you who believe! be not like those who disbelieve and say of their brethren when they travel in the earth or engage in fighting: Had they been with us, they would not have died and they would not have been slain; so Allah makes this to be an intense regret in their hearts; and Allah gives life and causes death and Allah sees what you do.

(3) Then Allah sent a crow digging up the earth so that he might show him how he should cover the dead body of his brother. He said: Woe me! do I lack the strength that I should be like this crow and cover the dead body of my brother? So he became of those who regret.

(4) But you will see those in whose hearts is a disease hastening towards them, saying: We fear lest a calamity should befall us; but it may be that Allah will bring the victory or a punishment from Himself, so that they shall be regretting on account of what they hid in their souls.

(5) Surely those who disbelieve spend their wealth to hinder (people) from the way of Allah; so they shall spend it, then it shall be to them an intense regret, then they shall be overcome; and those who disbelieve shall be driven together to hell.

(6) And if every soul that has done injustice had all that is in the earth, it would offer it for ransom, and they will manifest regret when they see the chastisement and the matter shall be decided between them with justice and they shall not be dealt with unjustly.

(7) And warn them of the day of intense regret, when the matter shall have been decided; and they are (now) in negligence and they do not believe.

(8) But they hamstrung her, then regretted;

(9) And those who were deemed weak shall say to those who were proud. Nay, (it was) planning by night and day when you told us to disbelieve in Allah and to set up likes with Him. And they shall conceal regret when they shall see the punishment; and We will put shackles on the necks of those who disbelieved; they shall not be requited but what they did.