Hypocrisy means making an outward display of Islam whilst inwardly concealing kufr.
Ayah’s about hyprocrisy in Quran:
“Verily, the hypocrites will be in the lowest depth (grade) of the Fire; no helper will you find for them[al-Nisaa’ 4:145]
“(They are) swaying between this and that, belonging neither to these nor to those; and he whom Allaah sends astray, you will not find for him a way (to the truth — Islam)”[al-Nisaa’ 4:143]
“And when it is said to them: ‘Come to what Allaah has sent down and to the Messenger (Muhammad),’ you (Muhammad) see the hypocrites turn away from you (Muhammad) with aversion” [al-Nisaa’ 4:61]
“And when they meet those who believe, they say: “We believe,” but when they are alone with their Shayaateen (devils — polytheists, hypocrites), they say: “Truly, we are with you; verily, we were but mocking. Allaah mocks at them and gives them increase in their wrong-doing to wander blindly”[al-Baqarah 2:14-15]
“And when it is said to them (hypocrites): ‘Believe as the people (followers of Muhammad, Al-Ansaar and Al-Muhaajiroon) have believed,’ they say: ‘Shall we believe as the fools have believed?’ Verily, they are the fools, but they know not”[al-Baqarah 2:13]
Some characteristics of hypocrites:
when he speaks, he lies;
when he makes a treaty, he betrays it;
when he makes a promise, he breaks it;
when he quarrels, he resorts to insults.
Their concern is with appearances and fancy speech whilst they are inwardly corrupt.
“There are four (characteristics), whoever has all of them is a complete hypocrite, and whoever has some of them has some element of hypocrisy, unless he gives it up: when he speaks, he lies; when he makes a treaty, he betrays it; when he makes a promise, he breaks it; when he quarrels, he resorts to insults.”(Narrated by Muslim, 53)