The word(s) "ungrateful" appears 26 time(s) in 24 verse(s) in Quran in Abdullah Yusuf Ali translation.

(21) If then they run away, We have not sent thee as a guard over them. Thy duty is but to convey (the Message). And truly, when We give man a taste of a Mercy from Ourselves, he doth exult thereat, but when some ill happens to him, on account of the deeds which his hands have sent forth, truly then is man ungrateful!

(22) "For, if Thou dost leave (any of) them, they will but mislead Thy devotees, and they will breed none but wicked ungrateful ones.

(23) We showed him the Way: whether he be grateful or ungrateful (rests on his will).

(24) Truly man is, to his Lord, ungrateful;