Mishkat al-Masabih 4 Prayer كتاب الصلاة 309

وَعَنْ أَبِي قَتَادَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَسْوَأُ النَّاسِ سَرِقَةً الَّذِي يَسْرِقُ مِنْ صَلَاتِهِ» . قَالُوا: يَا رَسُولَ اللَّهِ وَكَيْفَ يَسْرِقُ مِنْ صَلَاتِهِ؟ قَالَ: لَا يتم ركوعها وَلَا سجودها “. رَوَاهُ أَحْمد

Abu Qatada reported God’s Messenger as saying, “The one who commits the worst theft is he who steals from his prayer.” When asked how one could steal from his prayer he replied, “By not performing his bowing and his prostration perfectly.” Ahmad transmitted it.