The word(s) "secrets" appears 19 time(s) in 19 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) What! Do they say, "He has forged a falsehood against Allah"? But if Allah willed, He could seal up thy heart. And Allah blots out Vanity, and proves the Truth by His Words. For He knows well the secrets of all hearts.

(12) Or do they think that We hear not their secrets and their private counsels? Indeed (We do), and Our messengers are by them, to record.

(13) This, because they said to those who hate what Allah has revealed, "We will obey you in part of (this) matter"; but Allah knows their (inner) secrets.

(14) "Verily Allah knows the secrets of the heavens and the earth: and Allah Sees well all that ye do."

(15) Or have they a ladder, by which they can (climb up to heaven and) listen (to its secrets)? Then let (such a) listener of theirs produce a manifest proof.

(16) He merges Night into Day, and He merges Day into Night; and He has full knowledge of the secrets of (all) hearts.

(17) He knows what is in the heavens and on earth; and He knows what ye conceal and what ye reveal: yea, Allah knows well the (secrets) of (all) hearts.

(18) And whether ye hide your word or publish it, He certainly has (full) knowledge, of the secrets of (all) hearts.

(19) 'And we pried into the secrets of heaven; but we found it filled with stern guards and flaming fires.