The word(s) "disbelief" appears 37 time(s) in 35 verse(s) in Quran in Muhammad Pickthal translation.

(21) They swear by Allah that they said nothing (wrong), yet they did say the word of disbelief, and did disbelieve after their Surrender (to Allah). And they purposed that which they could not attain, and they sought revenge only that Allah by His messenger should enrich them of His bounty. If they repent it will be better for them; and if they turn away, Allah will afflict them with a painful doom in the world and the Hereafter, and they have no protecting friend nor helper in the earth.

(22) The wandering Arabs are more hard in disbelief and hypocrisy, and more likely to be ignorant of the limits which Allah hath revealed unto His messenger. And Allah is Knower, Wise.

(23) And as for those who chose a place of worship out of opposition and disbelief, and in order to cause dissent among the believers, and as an outpost for those who warred against Allah and His messenger aforetime, they will surely swear: We purposed naught save good. Allah beareth witness that they verily are liars.

(24) Is it (only) then, when it hath befallen you, that ye will believe? What! (Believe) now, when (until now) ye have been hastening it on (through disbelief)?

(25) Whoso disbelieveth in Allah after his belief - save him who is forced thereto and whose heart is still content with the Faith - but whoso findeth ease in disbelief: On them is wrath from Allah. Theirs will be an awful doom.

(26) And verily We have displayed for mankind in this Qur'an all kind of similitudes, but most of mankind refuse aught save disbelief.

(27) Have they not seen that Allah Who created the heavens and the earth is Able to create the like of them, and hath appointed for them an end whereof there is no doubt? But the wrong-doers refuse aught save disbelief.

(28) And as for the lad, his parents were believers and we feared lest he should oppress them by rebellion and disbelief.

(29) Whoso disbelieveth must (then) bear the consequences of his disbelief, while those who do right make provision for themselves -

(30) And if We sent a wind and they beheld it yellow, they verily would still continue in their disbelief.