Is it obligatory for us to make up a day in Ramadan?

If the people of various towns agree on the moon sighting, and a Muslim fasts for twenty-nine or thirty days based on their sighting, then there is no make-up fast due for him. This is based on the Prophet's (peace be upon him) saying: "The fast is on the day you fast, the Eid al-Fitr is on the day you break your fast, and the Eid al-Adha is on the day you offer your sacrifices." This hadith is interpreted to mean that fasting and breaking the fast should be done with the Muslim community. However, if a Muslim fasts for less than twenty-nine days, then he must make up the remaining days to complete the month to twenty-nine days.