The word(s) "concern" appears 52 time(s) in 50 verse(s) in Quran in Abdullah Yusuf Ali translation.

(21) (Some) say they were three, the dog being the fourth among them; (others) say they were five, the dog being the sixth,- doubtfully guessing at the unknown; (yet others) say they were seven, the dog being the eighth. Say thou: "My Lord knoweth best their number; It is but few that know their (real case)." Enter not, therefore, into controversies concerning them, except on a matter that is clear, nor consult any of them about (the affair of) the Sleepers.

(22) The other said: "If then thou wouldst follow me, ask me no questions about anything until I myself speak to thee concerning it."

(23) They ask thee concerning Zul-qarnain. Say, "I will rehearse to you something of his story."

(24) They ask thee concerning the Mountains: say, "My Lord will uproot them and scatter them as dust;

(25) Those who reject Faith will not cease to be in doubt concerning (Revelation) until the Hour (of Judgment) comes suddenly upon them, or there comes to them the Penalty of a Day of Disaster.

(26) "Allah will judge between you on the Day of Judgment concerning the matters in which ye differ."

(27) Pharaoh said: "O Chiefs! no god do I know for you but myself: therefore, O Haman! light me a (kiln to bake bricks) out of clay, and build me a lofty palace, that I may mount up to the god of Moses: but as far as I am concerned, I think (Moses) is a liar!"

(28) That (Allah) may question the (custodians) of Truth concerning the Truth they (were charged with): And He has prepared for the Unbelievers a grievous Penalty.

(29) Men ask thee concerning the Hour: Say, "The knowledge thereof is with Allah (alone)": and what will make thee understand?- perchance the Hour is nigh!

(30) But he had no authority over them,- except that We might test the man who believes in the Hereafter from him who is in doubt concerning it: and thy Lord doth watch over all things.