(Communion with Allāh:) The particular thing by which you should purify your religion for Allāh should be the fulfilment of those obligations which are especially for Him. Therefore, devote to Allāh some of your physical activity during the night and the day, and whatever (worship) you perform for seeking nearness to Allāh should be complete, without defect or deficiency, whatsoever physical exertion it may involve.