Sayyiduna Abu Qatadah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "The worst of people in stealing is the one who steals from his prayer." The Companions (may Allah be pleased with them) asked: O Messenger of Allah, how does one steal from the prayer? He (peace and blessings be upon him) said: "By not completing its bowing and its prostrations."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3996