The word(s) "sincere" appears 38 time(s) in 38 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) They said: "O our father! why dost thou not trust us with Joseph,- seeing we are indeed his sincere well-wishers?

(12) And (with passion) did she desire him, and he would have desired her, but that he saw the evidence of his Lord: thus (did We order) that We might turn away from him (all) evil and shameful deeds: for he was one of Our servants, sincere and purified.

(13) "Except Thy servants among them, sincere and purified (by Thy Grace)."

(14) (Allah) said: "This (way of My sincere servants) is indeed a way that leads straight to Me.

(15) It is no fault in the blind nor in one born lame, nor in one afflicted with illness, nor in yourselves, that ye should eat in your own houses, or those of your fathers, or your mothers, or your brothers, or your sisters, or your father's brothers or your father's sisters, or your mother's brothers, or your mother's sisters, or in houses of which the keys are in your possession, or in the house of a sincere friend of yours: there is no blame on you, whether ye eat in company or separately. But if ye enter houses, salute each other - a greeting of blessing and purity as from Allah. Thus does Allah make clear the signs to you: that ye may understand.

(16) And we ordained that he refused suck at first, until (His sister came up and) said: "Shall I point out to you the people of a house that will nourish and bring him up for you and be sincerely attached to him?"...

(17) And there came a man, running, from the furthest end of the City. He said: "O Moses! the Chiefs are taking counsel together about thee, to slay thee: so get thee away, for I do give thee sincere advice."

(18) Now, if they embark on a boat, they call on Allah, making their devotion sincerely (and exclusively) to Him; but when He has delivered them safely to (dry) land, behold, they give a share (of their worship to others)!-

(19) When a wave covers them like the canopy (of clouds), they call to Allah, offering Him sincere devotion. But when He has delivered them safely to land, there are among them those that halt between (right and wrong). But none reject Our Signs except only a perfidious ungrateful (wretch)!

(20) But the sincere (and devoted) Servants of Allah,-