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

(11) assuredly it is thy Lord Who will gather them together: for He is perfect in Wisdom and Knowledge.

(12) "We have brought to thee that which is inevitably due, and assuredly we tell the truth.

(13) For We assuredly sent amongst every People a messenger, (with the Command), "Serve Allah, and eschew Evil": of the People were some whom Allah guided, and some on whom error became inevitably (established). So travel through the earth, and see what was the end of those who denied (the Truth).

(14) To those who leave their homes in the cause of Allah, after suffering oppression,- We will assuredly give a goodly home in this world; but truly the reward of the Hereafter will be greater. If they only realised (this)!

(15) To every People have We appointed rites and ceremonies which they must follow: let them not then dispute with thee on the matter, but do thou invite (them) to thy Lord: for thou art assuredly on the Right Way.

(16) They said: "If thou desist not, O Lut! thou wilt assuredly be cast out!"

(17) And those who had envied his position the day before began to say on the morrow: "Ah! it is indeed Allah Who enlarges the provision or restricts it, to any of His servants He pleases! had it not been that Allah was gracious to us, He could have caused the earth to swallow us up! Ah! those who reject Allah will assuredly never prosper."

(18) That which We have revealed to thee of the Book is the Truth,- confirming what was (revealed) before it: for Allah is assuredly- with respect to His Servants - well acquainted and Fully Observant.

(19) assuredly the creation of the heavens and the earth is a greater (matter) than the creation of men: Yet most men understand not.

(20) To Him is referred the Knowledge of the Hour (of Judgment: He knows all): No date-fruit comes out of its sheath, nor does a female conceive (within her womb) nor bring forth the Day that (Allah) will propound to them the (question), "Where are the partners (ye attributed to Me?" They will say, "We do assure thee not one of us can bear witness!"