Augustine of Hippo

(Ep. 54. 7.) And as they were eating, whereby it is clearly seen that at their first partaking of the Lord’s Body and Blood, the disciples did not partake fasting. But are we therefore to except against the practice of the whole Church, of receiving fasting? It has seemed good to the Holy Ghost, that for the better honour of so great a Sacrament, the Lord’s Body should enter the Christian’s mouth before other food. For to commend more mightily the depth of this mystery, the Saviour chose this as the last thing He would imprint on the hearts and memory of His disciples, from whom He was to depart to His Passion. But He did not direct in what order it should thenceforth be taken, that He might reserve that for the Apostles by whom He would regulate His Church.