Hadith 268

And Ahmad has: "Keep your back straight till the bones return (to their positions)."

وَفِي لَفْظٍ لِأَحْمَدَ : { فَأَقِمْ صُلْبَكَ حَتَّى تَرْجِعَ اَلْعِظَامُ } <sup>1</sup>‏