The word(s) "brethren" appears 21 time(s) in 21 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) To the 'Ad People (We sent) Hud, one of their own brethren. He said: "O my people! worship Allah! ye have no other god but Him. (Your other gods) ye do nothing but invent!

(12) To the Thamud People (We sent) Salih, one of their own brethren. He said: "O my people! Worship Allah: ye have no other god but Him. It is He Who hath produced you from the earth and settled you therein: then ask forgiveness of Him, and turn to Him (in repentance): for my Lord is (always) near, ready to answer."

(13) To the Madyan People (We sent) Shu'aib, one of their own brethren: he said: "O my people! worship Allah: Ye have no other god but Him. And give not short measure or weight: I see you in prosperity, but I fear for you the penalty of a day that will compass (you) all round.

(14) Verily in Joseph and his brethren are signs (or symbols) for seekers (after Truth).

(15) The (brethren) sold him for a miserable price, for a few dirhams counted out: in such low estimation did they hold him!

(16) Then came Joseph's brethren: they entered his presence, and he knew them, but they knew him not.

(17) Verily Allah knows those among you who keep back (men) and those who say to their brethren, "Come along to us", but come not to the fight except for just a little while.

(18) Mention (Hud) one of 'Ad's (own) brethren: Behold, he warned his people about the winding Sand-tracts: but there have been warners before him and after him: "Worship ye none other than Allah: Truly I fear for you the Penalty of a Mighty Day."

(19) The 'Ad, Pharaoh, the brethren of Lut,

(20) And those who came after them say: "Our Lord! Forgive us, and our brethren who came before us into the Faith, and leave not, in our hearts, rancour (or sense of injury) against those who have believed. Our Lord! Thou art indeed Full of Kindness, Most Merciful."