God is showing us here that the lamb they used for blood on the doorpost was the same lamb they ate for the journey. In other words, everything that is necessary for living the life comes from the lamb. It isn't that the lamb dies for and then you're sent out to do the rest on your own (with His help,of course). The lamb is the total answer. The lamb that gave its blood for them also gave its life to them. They took its meat into them, and that became their nourishment, strength, and vitality for the journey. They lived their life out of the lamb's life. They walked in its energy. They killed one lamb for two purposes: for the Passover and for the walk.
--Dan Stone pg. 58, "The Rest of the Gospel"