NAMAAZ OF A MU'MIN
Allah Ta'ala states in The Holy Quran:
'Undoubtedly, the believers reached to their goal'
'Those who beseech in their prayers'
'And those who turn away from vain talk'
(Surah Al-Mo'minoon. verse 1,2,3)
The believers are the successful, who are humble in their Namaaz, and who avoid all that is nonsense.
Those who fear offending Allah Ta'ala will keep their parts of the body motionless in Namaaz. A Mu'min's Namaaz should be in the following manner:
' The namaazi should be thoroughly absorbed in Namaaz
' The namaazi should withdraw from worldly matters
' The namaazi should save oneself from activities of sinful disobedience to Allah Taala by not sighting out of the prayer mat, by not giving way to useless acts and movements, by not hanging both ends of shawl from shoulder, by not indulging in finger cracking, and by not looking skywards.
(Tafseer Noor Ul Irfaan with English translation of Kanzul Imaan)
By performing Namaaz in such a manner, the diginity of a Mu'min is established.
NAMAAZ OF A HYPOCRITE (MUNAFIQ)
Allah Ta'ala states in The Holy Quran:
'Who are neglectful of their salaah'
'Those who show it (to others)'
(Surah Al-Ma'oon. verse 5,6)
These verses were revealed regarding hypocrites like Abdullah Bin Ubay etc., who would sometimes perform Namaaz with total lack of devotion and love, not out of belief, but in order to show the believers that they are Namaazi, but in real sense they are far away from the worship of Allah Ta'ala.
Prophet Muhammad ﷺ said, 'the worst of thieves is the one who steals his prayer'. The companions(Radi Allaahu Anhum) asked, 'Ya RasoolUAllah ﷺ! How does he steal his prayer?' Prophet ﷺ replied, 'he does not do ruku or sajda properly'.
(Musnad Ahmad, and more)
In the commentary of this hadith, Hazrat Mufti Ahmad Yar Khan(Rahmatullah Alaih) says that a Namaaz thief is worse than the monetary thief because a monetary thief may gain in this world but will be punished in the hereafter. A Namaaz thief will be punished in the hereafter and will not gain anything in this world. A worldly thief betrays people but a Namaaz thief betrays Allah Ta'ala.