Allah Most High describes the hypocrites saying,
When they stood up to prayer, they stand without earnestness, to see of men, but little do they hold Allah in remembrance. (An-Nisa: 142)
He Most High also says,
So woe to the worshippers who are neglectful of their prayers, those who (want but) to be seen, but refuse (to supply) even) neighbourly needs. (Al-Maun: 4-7)
O ye who believe! Cancel not your charity by reminders of your generosity or by injury-like those who spend their wealth to be seen of men. (Al-Baqarah: 264)
Whoever expects to meet his Lord, let him work righteousness, and, in the worship of his Lord, admit no one as partner. (Al-Kahf: 110)
On the authority of Abu Hurairah (may Allah be pleased with him) who said that the Messenger of Allah (pbuh) said,
"The first of people who will be judged on the Day of Judgment will be a man who has died a martyr. He will be brought and Allah will make known to him His Favours and he will recognize them. (Allah) will say: And what did you do with them? He will say: I fought for you until I died a martyr. He will say: You have lied. You did but fight so that it might be said (of you): He is courageous. And so it was said. Then he will be ordered to be dragged on his face until he is cast into Hell-Fire. (Next) will be a man who has studied (religious) knowledge and has taught it and who used to recite the Quran. He will be brought and Allah will make known to him His Favours and he will recognize them. (Allah) will say: And what did you do with them? He will say: I studied (religious) knowledge and taught it and I recited the Quran for Your sake. He will say: You have lied. You did but study (religious) knowledge so that it might be said (of you): He is learned. And you recited the Quran that it might be said (of you): He is a reciter. And so it was said. Then he will be ordered to be dragged on his face until he is cast into Hell-fire. (Then) will come a man whom Allah had made rich and to whom He had given all kinds of wealth. He will be brought and Allah will make known to him His Favours and he will recognize them. (Allah) will say: And what did you do with them? He will say: I have left no way in which You like money to be spent without spending for Your sake. He will say: You have lied. You did but do so that it might be said (of you): He is generous. And so it was said. Then he will be ordered to be dragged on his face until he is cast into Hell-Fire.” [Muslim]
Al-Khattabi said, "The unfaithful men who seek people and fame with their deeds would be presented on the Day of Judgment, with all their concealed and unknown defects and faults."
The Messenger of Allah (pbuh) illustrated further,
"It is shirk (association), to seek people even with the slightest deeds.” [Ibn Majah]
He (pbuh) also said,
"For you my greatest fear is from minor Shirk (association)." people said, "What is the minor shirk, O Messenger of Allah?" He debarred, "Showing off (is that minor shirk)." Allah Most High will say on the Day of Judgment, "O you who have sought people with their actions, go to them and see if they could compensate you!" But something will confront them from Allah, which they could never have counted upon! (Al-Zumar: 47)
In their explanation to this verse, some scholars said, those people used to act seemingly good deeds, which would appear Off the Day of Judgment to evil deeds.
Some of the successors used to say when reading this verse, Woe to those who seek people by their deeds. It is said further that on the Day of Judgment those people would be called by four titles: Hypocrite, deceiver, unfaithful and loser, go to the people for whose sake you have done and take your compensation since we have no compensation for you."
Al-Hassan also commented, "Wishing to overcome the Decree of Allah, the hypocrites try to appear as righteous men. However, Allah would unveil their true reality before the faithful believers."
Qatadah said, "When the person did acts to be seen by people, Allah, the Almighty says, 'look at my servant how he disregards Me.'"
Umar Ibn Al-Khattab once saw a man declining his head in Prayer, therefore he said, "O you who decline his head, raise your head, for mindfulness exists in the heart only."
Abu Umamah saw a man weeping in Prayer in the mosque, whereupon he said, "O man, is it not better to do this in your house! (i.e., to be away from people)" Muhammad Ibn Al-Mubarak used to say "It is better for everyone to show mindfulness and God-consciousness at night (in his house) for it will be solely for the Creator, whereas showing God-consciousness at day may be for the created."
Ali Ibn Abi Talib (May Allah be pleased with him) said, "There are three signs for the one who works to be shown by people: Inactivity when alone and activity before people, love for estimation and abhorrence to criticism."
Al-Fudail Ibn Aiad said, "Riya (showing off) is to leave work because of people, shirk (association) is to work for the sake of people, while sincerity is to be saved from the two staffs by Allah.
Ascribing Associates To Allah, the Most High (Shirk)
Killing A Human Being
Not Performing The Prayer
Not Paying Zakat
Breaking One's Fast During Ramadan Without An Excuse
Not Performing the Hajj when Able to
Showing Disrespect to One's Parents
Severing the Ties of One's Relatives
Accepting Usurious Gain
Wrong Consuming An Orphan's Property
Lying About The Prophet
Fleeing From The Battlefield
The Leader Who Misleads His Followers, The Tyrant And The Oppressor
Arrogance, Pride, Conceit, Vanity And Haughtiness
Bearing False Witness
Accusing A Woman Of Adultery
Misappropriating Spoils Of War, Muslim Funds Or Zakat
Highwaymen Who Menace The Road
The Engulfing Oath
Taking People's Property Through Falsehood
The Consumption of Haram
The Dishonest Judge
Women Imitating Men And Vice Versa
The Pimp and the one Who Permits His Wife to Fornicate
Marrying Solely To Return To The Previous Husband
Not Freeing Oneself Of All Traces Of Urine
Showing Off In Good Work
Learning Sacred Knowledge For The Sake Of This World, Or Concealing It
Breach of Trust
Reminding Recipients of Ones Charity To Them
Disbelieving In Destiny (qadar)
Listening To People's Private Conversations
The Talebearer Who Stirs Up Enmity Between People
Breaking Promises or Pledges
Believing Fortune Tellers And Astrologers
Wife Rebelling Against Her Husband