Hazrat Zaid bin Wahb narrates that Hazrat Hudhaifa (may Allah be pleased with him) once entered the mosque and saw that a man was praying towards the doors of Kindah, but he was not performing the bowing (ruku) and prostration (sajda) properly. When the man completed his prayer, Hazrat Hudhaifa (may Allah be pleased with him) asked him, "For how long have you been praying like this?" He replied, "For forty years." Hazrat Hudhaifa (may Allah be pleased with him) said, "You have not prayed for forty years. If you had died while praying in this manner, you would have departed from this world on a way other than the way of the Messenger of Allah (peace and blessings be upon him)." Then Hazrat Hudhaifa (may Allah be pleased with him) began to teach him how to pray and said, "A person may lighten the prayer, but he should not be deficient in bowing and prostration."

It is narrated from Hasan that the Messenger of Allah, peace and blessings be upon him, said: "The worst thief is the one who steals in prayer." The people asked, "O Messenger of Allah! How can one steal in prayer?" He replied, "By not performing its bowing and prostration properly."

Hazrat Hamla bin Abdur Rahman narrates that Hazrat Ubadah saw a man who was not performing ruku and sujood properly. He took hold of that man's hand, so the man became frightened. Hazrat Ubadah said, "Do not imitate him or those like him. And remember that there is no prayer without Surah Al-Fatiha."

Hazrat Abu Ja'far narrates that the Noble Prophet (peace and blessings be upon him) saw a man who was prostrating in such a manner as if he was striking his head on the ground. Upon seeing him, the Prophet said: "If this person dies upon this prayer, he will not die upon my religion."

Hazrat Abu Yahya narrates that Hazrat Abu Hurairah saw a woman who was praying in such a manner as if a hen was pecking. Upon seeing her, he said, "You are lying."

Hasan narrates that Hazrat Saeed bin Musayyib saw a man who was not performing the bowing and prostration properly. He scolded him and said, "You have ruined your prayer."

Hazrat A’mash says that I saw Hazrat Anas bin Malik (may Allah be pleased with him) performing prayer near the Ka’bah in Makkah. I did not come in front of him. He was offering the prayer with utmost calmness; when he would rise from bowing (ruku’), he would stand completely straight, to the extent that even the veins of his stomach would become straight.

Hazrat Ibn Abi Laila narrates that a man entered the mosque and performed prayer in such a way that he did not perform the bowing and prostration properly. I mentioned this to Hazrat Abdullah bin Yazid, so he said that it would have been better if he had not performed the prayer at all.

Hazrat Ali (may Allah be pleased with him) bin Zaid narrates that Hazrat Miswar bin Makhramah saw a man who was not performing the bowing and prostration properly. He said to him, "Repeat your prayer." The man refused to repeat the prayer, but he did not leave him until he performed the prayer again.

Hazrat Musa bin Muslim says that Hazrat Tawus was sitting when a man was performing prayer and was not performing the bowing and prostration properly. A man said that his prayer is not valid. Hazrat Tawus said, "Leave him; whatever prayer he has performed, its reward has been written in his book of deeds."