there can be no difficulty to the prophet in what allah has indicated to him as a duty. it was the practice of allah amongst those of old that have passed away. and the command of allah is a decree determined.
ما كان على النبي من حرج فيما فرض الله له سنة الله في الذين خلوا من قبل وكان أمر الله قدرا مقدورا