The word(s) "fail" appears 37 time(s) in 37 verse(s) in Quran in Abdullah Yusuf Ali translation.

(31) But it is for those who fear their Lord. That lofty mansions, one above another, have been built: beneath them flow rivers (of delight): (such is) the Promise of Allah: never doth Allah fail in (His) promise.

(32) For those who believe and work deeds of righteousness is a reward that will never fail.

(33) The similitude of those who were charged with the (obligations of the) Mosaic Law, but who subsequently failed in those (obligations), is that of a donkey which carries huge tomes (but understands them not). Evil is the similitude of people who falsify the Signs of Allah: and Allah guides not people who do wrong.

(34) Nay, verily for thee is a Reward unfailing:

(35) Except to those who believe and work righteous deeds: For them is a Reward that will never fail.

(36) And he fails that corrupts it!

(37) Except such as believe and do righteous deeds: For they shall have a reward unfailing.