The word(s) "believer" appears 309 time(s) in 259 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) If Allah helps you, none can overcome you: If He forsakes you, who is there, after that, that can help you? in Allah, then, Let believers put their trust.

(12) Allah did confer a great favour on the believers when He sent among them a messenger from among themselves, rehearsing unto them the Signs of Allah, sanctifying them, and instructing them in Scripture and Wisdom, while, before that, they had been in manifest error.

(13) What ye suffered on the day the two armies Met, was with the leave of Allah, in order that He might test the believers,-

(14) Let not the Unbelievers think that our respite to them is good for themselves: We grant them respite that they may grow in their iniquity: But they will have a shameful punishment.

(15) Allah will not leave the believers in the state in which ye are now, until He separates what is evil from what is good nor will He disclose to you the secrets of the Unseen. But He chooses of His Messengers (For the purpose) whom He pleases. So believe in Allah. And His messengers: And if ye believe and do right, ye have a reward without measure.

(16) Let not the strutting about of the Unbelievers through the land deceive thee:

(17) Hast thou not turned Thy vision to those who were given a portion of the Book? they believe in sorcery and Evil, and say to the Unbelievers that they are better guided in the (right) way Than the believers!

(18) Then fight in Allah's cause - Thou art held responsible only for thyself - and rouse the believers. It may be that Allah will restrain the fury of the Unbelievers; for Allah is the strongest in might and in punishment.

(19) Never should a believer kill a believer; but (If it so happens) by mistake, (Compensation is due): If one (so) kills a believer, it is ordained that he should free a believing slave, and pay compensation to the deceased's family, unless they remit it freely. If the deceased belonged to a people at war with you, and he was a believer, the freeing of a believing slave (Is enough). If he belonged to a people with whom ye have treaty of Mutual alliance, compensation should be paid to his family, and a believing slave be freed. For those who find this beyond their means, (is prescribed) a fast for two months running: by way of repentance to Allah: for Allah hath all knowledge and all wisdom.

(20) If a man kills a believer intentionally, his recompense is Hell, to abide therein (For ever): And the wrath and the curse of Allah are upon him, and a dreadful penalty is prepared for him.