The word(s) "firm" appears 59 time(s) in 56 verse(s) in Quran in Muhammad Pickthal translation.

(11) O ye unto whom the Scripture hath been given! Believe in what We have revealed confirming that which ye possess, before We destroy countenances so as to confound them, or curse them as We cursed the Sabbath-breakers (of old time). The commandment of Allah is always executed.

(12) And We caused the Mount to tower above them at (the taking of) their covenant: and We bade them: Enter the gate, prostrate! and We bode them: Transgress not the Sabbath! and We took from them a firm covenant.

(13) But those of them who are firm in knowledge and the believers believe in that which is revealed unto thee, and that which was revealed before thee, especially the diligent in prayer and those who pay the poor-due, the believers in Allah and the Last Day. Upon these We shall bestow immense reward.

(14) And We caused Jesus, son of Mary, to follow in their footsteps, confirming that which was (revealed) before him in the Torah, and We bestowed on him the Gospel wherein is guidance and a light, confirming that which was (revealed) before it in the Torah - a guidance and an admonition unto those who ward off (evil).

(15) And unto thee have We revealed the Scripture with the truth, confirming whatever Scripture was before it, and a watcher over it. So judge between them by that which Allah hath revealed, and follow not their desires away from the truth which hath come unto thee. For each We have appointed a divine law and a traced-out way. Had Allah willed He could have made you one community. But that He may try you by that which He hath given you (He hath made you as ye are). So vie one with another in good works. Unto Allah ye will all return, and He will then inform you of that wherein ye differ.

(16) See they not how many a generation We destroyed before them, whom We had established in the earth more firmly than We have established you, and We shed on them abundant showers from the sky, and made the rivers flow beneath them. Yet we destroyed them for their sins, and created after them another generation.

(17) And this is a blessed Scripture which We have revealed, confirming that which (was revealed) before it, that thou mayst warn the Mother of Villages and those around her. Those who believe in the Hereafter believe herein, and they are careful of their worship.

(18) When He made the slumber fall upon you as a reassurance from him and sent down water from the sky upon you, that thereby He might purify you, and remove from you the fear of Satan, and make strong your hearts and firm (your) feet thereby.

(19) When thy Lord inspired the angels, (saying): I am with you. So make those who believe stand firm. I will throw fear into the hearts of those who disbelieve. Then smite the necks and smite of them each finger.

(20) O ye who believe! When ye meet an army, hold firm and think of Allah much, that ye may be successful.