The Messenger of Allah ﷺ said, "The worst thief among people is the one who steals from his prayer."They asked, "Messenger of Allah, how does he steal from his prayer?"He replied, "He does not complete its bowing and prostration," or he said, "He does not straighten his back in the bowing and prostration."
حدثنا محمد بن النوشجان وهو أبو جعفر السويدي حدثنا الوليد بن مسلم عن الأوزاعي عن يحيى بن أبي كثير
قال رسول الله ﷺ أسوأ الناس سرقة الذي يسرق من صلاته قالوا يا رسول الله وكيف يسرق من صلاته قال لا يتم ركوعها ولا سجودها أو قال لا يقيم صلبه في الركوع والسجود
Its isnad is sahih. Muhammad bin Nawshajan Abu Jafar Suwaydi was deemed reliable by Ibn Hibban and others. Abu Hatim did not know him. It is stated in al-Taajil, "The people of Iraq narrated from him." The hadith was narrated by Tabarani in al-Kabir 3/242, no. 3283, and Haythami said in 2/120, "Ahmad and Tabarani narrated it, and its men are the men of the Sahih." Al-Hakim graded it sahih in 1/229, and Dhahabi agreed with him. Munziri attributed it to those we mentioned and noted al-Hakim's grading it sahih. And al-Targhib 1/335.