The word(s) "firm" appears 74 time(s) in 72 verse(s) in Quran in Mohsin Khan translation.

(1) And believe in what I have sent down (this Qur'an), confirming that which is with you, [the Taurat (Torah) and the Injeel (Gospel)], and be not the first to disbelieve therein, and buy [get (تاخذ اجرا)] not with My Verses [the Taurat (Torah) and the Injeel (Gospel)] a small price (i.e. getting a small gain by selling My Verses), and fear Me and Me Alone. (Tafsir At-Tabari ).

(2) And when there came to them (the Jews), a Book (this Qur'an) from Allah confirming what is with them [the Taurat (Torah) and the Injeel (Gospel)], although aforetime they had invoked Allah (for coming of Muhammad صلى الله عليه وسلم) in order to gain victory over those who disbelieved, then when there came to them that which they had recognised, they disbelieved in it. So let the Curse of Allah be on the disbelievers.

(3) And when it is said to them (the Jews), "Believe in what Allah has sent down," they say, "We believe in what was sent down to us." And they disbelieve in that which came after it, while it is the truth confirming what is with them. Say (O Muhammad صلى الله عليه وسلم to them): "Why then have you killed the Prophets of Allah aforetime, if you indeed have been believers?"

(4) And (remember) when We took your covenant and We raised above you the Mount (saying), "Hold firmly to what We have given you and hear (Our Word)." They said, "We have heard and disobeyed." And their hearts absorbed (the worship of) the calf because of their disbelief. Say: "Worst indeed is that which your faith enjoins on you if you are believers."

(5) Say (O Muhammad صلى الله عليه وسلم): "Whoever is an enemy to Jibril (Gabriel) (let him die in his fury), for indeed he has brought it (this Qur'an) down to your heart by Allah's Permission, confirming what came before it [i.e. the Taurat (Torah) and the Injeel (Gospel)] and guidance and glad tidings for the believers.

(6) And when there came to them a Messenger from Allah (i.e. Muhammad صلى الله عليه وسلم) confirming what was with them, a party of those who were given the Scripture threw away the Book of Allah behind their backs as if they did not know!

(7) And when they advanced to meet Jalut (Goliath) and his forces, they invoked: "Our Lord! Pour forth on us patience, and set firm our feet and make us victorious over the disbelieving people."

(8) It is He Who has sent down the Book (the Qur'an) to you (O Muhammad صلى الله عليه وسلم) with truth, confirming what came before it. And He sent down the Taurat (Torah) and the Injeel (Gospel),

(9) It is He Who has sent down to you (Muhammad صلى الله عليه وسلم) the Book (this Qur'an). In it are Verses that are entirely clear, they are the foundations of the Book [and those are the Verses of Al-Ahkam (commandments), Al-Fara'id (obligatory duties) and Al-Hudud (legal laws for the punishment of thieves, adulterers)]; and others not entirely clear. So as for those in whose hearts there is a deviation (from the truth) they follow that which is not entirely clear thereof, seeking Al-Fitnah (polytheism and trials), and seeking for its hidden meanings, but none knows its hidden meanings save Allah. And those who are firmly grounded in knowledge say: "We believe in it; the whole of it (clear and unclear Verses) are from our Lord." And none receive admonition except men of understanding. (Tafsir At-Tabari).

(10) Then the angels called him, while he was standing in prayer in Al-Mihrab (a praying place or a private room), (saying): "Allah gives you glad tidings of Yahya (John), confirming (believing in) the word from Allah [i.e. the creation of 'Îsa (Jesus) عليه السلام, the Word from Allah ("Be!" - and he was!)], noble, keeping away from sexual relations with women, a Prophet, from among the righteous."