Riyaa is showing off and can include the desire to seek praise or a reputation. It includes worrying what people think of oneself. Showing-off includes one’s deeds for someone else’s sake when they should be done for the sake of Allah (SWT). Ibn ‘Abbas said: “Riyaa is more hidden than a black ant on a black stone in a dark night.”
Rasoolullah (SAW) said, “What I fear for you the most is the minor shirk, that is ar-riyaa. Allah will say on the Day of Judgment when He is rewarding the people for their actions: Go to those for whom you did riyaa for in the world then see if you find the reward with them” (Ahmad).
Rasoolullah (SAW) said, “Shall I not inform you of what I fear for you more than the maseeh ud-dajjaal (false messiah)? It is the hidden shirk (riyaa). It is when a man stands up for prayer, then beautifies his prayer for another to look at” (Ibn Majah).
Abu Huraira narrated that Rasoolullah (SAW) narrated a story about three people on the Day of Judgment. The first of the people whose case will be decided on Judgment Day will be a man who died as a martyr. He will be brought forth. God will make him know about His blessings (which He had bestowed on him in the World). The man will acknowledge them. Then God will ask him: What did you do with them? He will say: I fought in Your way until I died as a martyr. God will remark: You are lying. You fought so that you may be called a brave warrior. Then orders will be passed against him. So he will be dragged along on his face and cast into Hell. Second will be a man who studied religious knowledge. Then he taught it to others and recited the Quran. He will be brought for Judgment. God will remind him of His favors (showered on him in the world). He will admit them (having enjoyed them in his life). Then God will ask him: What did you do with them? He will reply: I acquired knowledge and imparted it and also recited the Quran for Your sake. God will observe: You have told a lie, for you got knowledge to be renowned as a scholar; and you recited the Quran to be marked as a Qari (one who recites the Quran according to the rules). Then orders will be passed against him. So he will be dragged along on his face and thrown into Hell. The third person will be a man to whom God had made abundantly rich and granted him every kind of wealth. He will be brought for judgment. God will let him know about His gifts conferred upon him in the world. He will recognize them. Then God will inquire: What did you with them? He will say: I left no way in which you like money to be spent without spending in it for your sake. God will say: You are lying. You did so to be described as generous and philanthropic in the society; It means you got your reward in the world according to your intention. Now you deserve nothing in the Hereafter except Hell. So orders will be passed against him and he will be dragged along on his face until he will be hurled into Hell.
Umar (ra) narrated that Rasoolullah (SAW) said, “The reward of deeds depends upon the intentions and every person will get the reward according to what he has intended. So whoever emigrated for worldly benefits or for a woman to marry, his emigration was for what he emigrated for.”