سنن ابن ماجه 872

It was narrated that Rashid said:“I heard Wabisah bin Ma’bad saying: ‘I saw the Messenger of Allah (ﷺ) performing prayer, and when he bowed he made his back so straight that if water were poured on it, it would have stayed there.’”

Rapporté par Rashid : J’ai entendu Wabisah bin Ma’bad dire : “J’ai vu le Messager d’Allah (ﷺ) faire la prière, et quand il s’inclinait, il gardait le dos si droit que si on avait versé de l’eau dessus, elle serait restée en place.”