The word(s) "regretful" appears 6 time(s) in 6 verse(s) in Quran in Saheeh International translation.

(1) Then Allah sent a crow searching in the ground to show him how to hide the disgrace of his brother. He said, "O woe to me! Have I failed to be like this crow and hide the body of my brother?" And he became of the regretful.

(2) So you see those in whose hearts is disease hastening into [association with] them, saying, "We are afraid a misfortune may strike us." But perhaps Allah will bring conquest or a decision from Him, and they will become, over what they have been concealing within themselves, regretful.

(3) [Allah] said, "After a little, they will surely become regretful."

(4) But they hamstrung her and so became regretful.

(5) How regretful for the servants. There did not come to them any messenger except that they used to ridicule him.

(6) O you who have believed, if there comes to you a disobedient one with information, investigate, lest you harm a people out of ignorance and become, over what you have done, regretful.