It is narrated from Hazrat Abu Saeed Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The worst thief is the one who steals in prayer." The companions (may Allah be pleased with them) asked, "O Messenger of Allah (peace and blessings be upon him)! How can one steal in prayer?" He replied, "By not performing the bowing (ruku) and prostration (sajdah) properly."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 11532
Hadith Gradingحکم دارالسلام:حديث حسن، وهذا إسناد ضعيف لضعف على بن زيد بن جدعان