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

(21) Except the sincere (and devoted) Servants of Allah.

(22) Except the sincere and devoted Servants of Allah (among them).

(23) Not (so do) the Servants of Allah, sincere and devoted.

(24) "We should certainly have been Servants of Allah, sincere (and devoted)!"

(25) "Except Thy Servants amongst them, sincere and purified (by Thy Grace)."

(26) Verily it is We Who have revealed the Book to thee in Truth: so serve Allah, offering Him sincere devotion.

(27) Is it not to Allah that sincere devotion is due? But those who take for protectors other than Allah (say): "We only serve them in order that they may bring us nearer to Allah." Truly Allah will judge between them in that wherein they differ. But Allah guides not such as are false and ungrateful.

(28) Say: "Verily, I am commanded to serve Allah with sincere devotion;

(29) Say: "It is Allah I serve, with my sincere (and exclusive) devotion:

(30) Call ye, then, upon Allah with sincere devotion to Him, even though the Unbelievers may detest it.