The word(s) "err" appears 111 time(s) in 111 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) Soon shall We cast terror into the hearts of the Unbelievers, for that they joined companions with Allah, for which He had sent no authority: their abode will be the Fire: And evil is the home of the wrong-doers!

(12) Allah did confer a great favour on the believers when He sent among them a messenger from among themselves, rehearsing unto them the Signs of Allah, sanctifying them, and instructing them in Scripture and Wisdom, while, before that, they had been in manifest error.

(13) Hast thou not turned Thy vision to those who were given a portion of the Book? they traffic in error, and wish that ye should lose the right path.

(14) Or do they envy mankind for what Allah hath given them of his bounty? but We had already given the people of Abraham the Book and Wisdom, and conferred upon them a great kingdom.

(15) When there comes to them some matter touching (Public) safety or fear, they divulge it. If they had only referred it to the Messenger, or to those charged with authority among them, the proper investigators would have Tested it from them (direct). Were it not for the Grace and Mercy of Allah unto you, all but a few of you would have fallen into the clutches of Satan.

(16) O ye who believe! When ye go abroad in the cause of Allah, investigate carefully, and say not to any one who offers you a salutation: "Thou art none of a believer!" Coveting the perishable goods of this life: with Allah are profits and spoils abundant. Even thus were ye yourselves before, till Allah conferred on you His favours: Therefore carefully investigate. For Allah is well aware of all that ye do.

(17) They ask thee for a legal decision. Say: Allah directs (thus) about those who leave no descendants or ascendants as heirs. If it is a man that dies, leaving a sister but no child, she shall have half the inheritance: If (such a deceased was) a woman, who left no child, Her brother takes her inheritance: If there are two sisters, they shall have two-thirds of the inheritance (between them): if there are brothers and sisters, (they share), the male having twice the share of the female. Thus doth Allah make clear to you (His law), lest ye err. And Allah hath knowledge of all things.

(18) Say: "Who is it that delivereth you from the dark recesses of land and sea, when ye call upon Him in humility and silent terror: 'If He only delivers us from these (dangers), (we vow) we shall truly show our gratitude'?"

(19) Lo! Abraham said to his father Azar: "Takest thou idols for gods? For I see thee and thy people in manifest error."

(20) A Book revealed unto thee,- So let thy heart be oppressed no more by any difficulty on that account,- that with it thou mightest warn (the erring) and teach the Believers).