Why did Allaah specify fasting by saying, ‘Fasting is for Me and I will reward [the fasting person] for it?’

Shaikh Uthaimeen, may Allaah have mercy on him was asked, “Why did Allaah, the Most High, specify fasting in His Saying, ‘Fasting is for Me and I will reward [the fasting person] for it?’”  So he replied, “Because the fasting person leaves his food, drink and desires for the Sake of Allaah, the Mighty and Majestic, in all those places where only his Lord can see him, so Allaah, the Most High, specified it for Himself because of the manifestation of total sincerity in it.”

Fataawaa Nurun-alad-Darb.