Hadith 300:1
Waki’ narrated to us, he said: ‘Ikrimah ibn ‘Ammar narrated to us, from ‘Abdullah ibn Zayd, or Badr—I am in doubt—from Talq ibn ‘Ali al-Hanafi, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah, the Almighty and Majestic, does not look at the prayer of a servant who does not straighten his back in it between his bowing and his prostration."
حدثنا وكيع، قال: حدثنا عكرمة بن عمار، عن عبد الله بن زيد، أو بدر أنا أشك عن طلق بن علي الحنفي قال: قال رسول الله صلى الله عليه وسلم: " لا ينظر الله عز وجل إلى صلاة عبد لا يقيم فيها صلبه بين ركوعها وسجودها "