Allah (swt) is addressing the Prophet (saws), telling him: Have you, O’ Muhammad, seen the one who denies the Recompense?
It is narrated that this Surah was revealed particularly because of Abo Jahl, or Abo Al-A’ss bin Wael, when he hit an orphan and pushed him, and the Prophet (saws) himself has witnessed this incident.
This is not a question, it is one of the styles of the Holy Qur’an to bring an announcement in a form of interrogative, that is Because Allah (swt) wants to share the addressee in the speech, as if the answer is not known by the humans, so He (swt) will tell about it.
Anyone who hears this question will think that the one who denies the Recompense is the one who disbelieves in Allah (swt) and His Prophet, who does not establish prayer, fast, or even does not give alms or practice pilgrimage. However, Allah (swt) wants to tell us that lying against the Recompense does not necessarily mean to deny the origin of faith or to disbelieve; the liar against the Recompense could be a believer but he does not follow the method of Allah (swt), does not submit to Allah’s (swt) commands nor refrain from what is forbidden, because applying the faith on deeds is the cornerstone of faith as Al-Hassan Al-Bassri (may Allah be pleased with him) said:
“Faith is what is settled in the heart and affirmed by the deeds’ 
It is easy of a Muslim to say that he is a believer, rather, it is not so easy to submit and act according to the method that he believes in.
 Mussanaf Ibn Abi Shaybah, The Book of faith, Hadith No. 30351