Setting
1- The Messenger of Allah (may Allah's peace and blessings be upon him) used to leave fasting in a certain month until we would think that he has not fasted at all that month; and he used to fast in another month so much that we would think he has not stopped fasting at all in that month. If one wished to see him praying at night, one could see him (in that state), and if one wished to see him sleeping at night, one could see him (in that state) too
2- The Messenger of Allah (may Allah's peace and blessings be upon him) prohibited Wisāl (continuous fasting for two days). So they said to him: But you practice Wisāl! He said: I am not like you. I am provided with food and drink (by my Lord)