The word(s) "fails" appears 3 time(s) in 3 verse(s) in Quran in Mohsin Khan translation.

(1) And they ask you to hasten on the torment! And Allah fails not His Promise. And verily, a day with your Lord is as a thousand years of what you reckon.

(2) (It is) a Promise of Allah (i.e. Allah will give victory to the Romans against the Persians), and Allah fails not in His Promise, but most of men know not.

(3) And indeed he fails who corrupts his ownself (i.e. disobeys what Allah has ordered by rejecting the true Faith of Islamic Monotheism or by following polytheism or by doing every kind of evil wicked deeds).