The word(s) "boast" appears 5 time(s) in 5 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) That they said (in boast), "We killed Christ Jesus the son of Mary, the Messenger of Allah";- but they killed him not, nor crucified him, but so it was made to appear to them, and those who differ therein are full of doubts, with no (certain) knowledge, but only conjecture to follow, for of a surety they killed him not:-

(2) "And swell not thy cheek (for pride) at men, nor walk in insolence through the earth; for Allah loveth not any arrogant boaster.

(3) Know ye (all), that the life of this world is but play and amusement, pomp and mutual boasting and multiplying, (in rivalry) among yourselves, riches and children. Here is a similitude: How rain and the growth which it brings forth, delight (the hearts of) the tillers; soon it withers; thou wilt see it grow yellow; then it becomes dry and crumbles away. But in the Hereafter is a Penalty severe (for the devotees of wrong). And Forgiveness from Allah and (His) Good Pleasure (for the devotees of Allah). And what is the life of this world, but goods and chattels of deception?

(4) In order that ye may not despair over matters that pass you by, nor exult over favours bestowed upon you. For Allah loveth not any vainglorious boaster,-

(5) He may say (boastfully); Wealth have I squandered in abundance!