This hadith emphasizes the importance of fasting during the month of Ramadan. It was narrated from Abu Hurairah that the Messenger of Allah said that if someone does not fast one day in Ramadan without having a concession allowing them to do so, then fasting for a lifetime will not make up for it. This hadith teaches us that we should take our religious obligations seriously and strive to fulfill them as best as we can. We should also remember to seek permission from Allah before taking any action which may go against His commands. Additionally, this hadith reminds us that even small acts can have great consequences and thus we should always strive to do what is right and avoid what is wrong.