One of the worst forms of theft or cheating is cheating in prayer.
The Messenger of Allah (peace and blessings of Allah be upon him) said: The worst type of thief is the one who steals from his prayer.
The people asked, O Messenger of Allah, how can a person steal from his prayer?
He said: By not doing rukoo and sujood properly.
(Reported by Imaam Ahmad, 5/310; see also Saheeh al-Jaami, 997).
This lack of composure and failure to pause in rukoo and sujood and to stand up straight after rukoo or sit up properly between sujoods may be observed in many of those who pray, and hardly any mosque is free of examples of people who do not have the proper composure in prayer. Correct composure is one of the pillars of prayer, without which prayer is invalid.
This is a serious matter.
The Prophet (peace and blessings of Allah be upon him) said: A man’s prayer is not good enough until his back is straight in rukoo and sujood.
(Reported by Abu Dawud, 1/533; see also Saheeh al-Jaamia 7224).