The word(s) "believer" appears 350 time(s) in 314 verse(s) in Quran in Muhammad Pickthal translation.

(31) And when thou settedst forth at daybreak from thy housefolk to assign to the believers their positions for the battle, Allah was Hearer, Knower.

(32) When two parties of you almost fell away, and Allah was their Protecting Friend. In Allah let believers put their trust.

(33) When thou didst say unto the believers: Is it not sufficient for you that your Lord should support you with three thousand angels sent down (to your help)?

(34) And ward off (from yourselves) the Fire prepared for disbelievers.

(35) Faint not nor grieve, for ye will overcome them if ye are (indeed) believers.

(36) And that Allah may prove those who believe, and may blight the disbelievers.

(37) Allah verily made good His promise unto you when ye routed them by His leave, until (the moment) when your courage failed you, and ye disagreed about the order and ye disobeyed, after He had shown you that for which ye long. Some of you desired the world, and some of you desired the Hereafter. Therefore He made you flee from them, that He might try you. Yet now He hath forgiven you. Allah is a Lord of Kindness to believers.

(38) If Allah is your helper none can overcome you, and if He withdraw His help from you, who is there who can help you after Him? In Allah let believers put their trust.

(39) Allah verily hath shown grace to the believers by sending unto them a messenger of their own who reciteth unto them His revelations, and causeth them to grow, and teacheth them the Scripture and wisdom; although before (he came to them) they were in flagrant error.

(40) That which befell you, on the day when the two armies met, was by permission of Allah; that He might know the true believers;