The word(s) "conceal" appears 36 time(s) in 35 verse(s) in Quran in Abdullah Yusuf Ali translation.

(31) They say: "Our hearts are under veils, (concealed) from that to which thou dost invite us, and in our ears in a deafness, and between us and thee is a screen: so do thou (what thou wilt); for us, we shall do (what we will!)"

(32) O ye who believe! Take not my enemies and yours as friends (or protectors),- offering them (your) love, even though they have rejected the Truth that has come to you, and have (on the contrary) driven out the Prophet and yourselves (from your homes), (simply) because ye believe in Allah your Lord! If ye have come out to strive in My Way and to seek My Good Pleasure, (take them not as friends), holding secret converse of love (and friendship) with them: for I know full well all that ye conceal and all that ye reveal. And any of you that does this has strayed from the Straight Path.

(33) 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.

(34) By the Night as it conceals it;

(35) By the Night as it conceals (the light);