Fasting the month of Ramadan is an obligation and a great worship. It is among the best acts of obedience. In Fasting there is great reward. Imam al-Bukhariyy related the Qudsiyy hadith that the Prophet peace to be upon him said that Allah said:
كُلُّ حَسَنة بعشْرِ أمثالها إلى سبعمائة ضعف إلّا الصّيام فإنَّهُ لي وأنا أجزي بِه
which means: <<The reward of every good deed is multiplied from ten up to seven-hundred times–except that of the Fasting–which is usually done in sincerity, will be multiplied by as many times as Allah wills.>>
One of the doors of Paradise, named ar-Rayyan, is specified for those Muslims who used to fast in this world. On the Day of Judgment it will be opened, and those who used to fast in obedience to Allah will be called to enter through that door. Then ar-Rayyan will be closed, and no others will enter through it.
The month of Ramadan is the ninth month of the lunar year. It is the best month of the year, as the night of al-Qadr in Ramadan is the best night of the year. Fasting became an obligation on the Muslims in the second year after the Prophetic emigration. Prophet Muhammed peace to be upon him fasted Ramadan for nine years after which he died.
The obligation on the believers of fasting Ramadan is known from the Qur’an and the hadith. It was explicitly stated in Verse 183 of Surat al-Baqarah:
يا أيها الذين آمنوا كتب عليكم الصيام كما كتب على الذين من قبلكم لعلكم تتقون
which means: [ O believers, Fasting is an obligation upon you as it was ordained upon the [Muslim nations] before you–to help you become pious.] Fasting was an obligation upon the nations before the nation of Prophet Muhammad peace to be upon him , however, fasting the month of Ramadan in particular is a specification for the nation of Prophet Muhammad peace to be upon him only.
Moreover, Prophet Muhammad peace to be upon him named Fasting (the month of Ramadan) as one of the five most important matters of Islam in the famous hadith known as “Hadith Jibril” as related by al-Bukhariyy and Muslim. Angel Jibril came to the Prophet in the shape of a man with white clothes and asked the Prophet to inform him about Islam. In response, the Prophet said:
الإسلام أن تشهد أن لا إله إلا الله وأن مُحمّدًا رسول الله، وتقيم الصلاة، وتؤتي الزكاة، وتصوم رمضان، وتحج البيت إن استطعت إليه سبيلًا
which means: <<Islam is bearing witness that no one is God except Allah and Muhammad is the Messenger of Allah, performing Prayer, paying Zakah, Fasting the month of Ramadan, and performing Pilgrimage if you are able. >>
Consequently, for the one who has learned of its obligation, renouncing the obligation of fasting the month of Ramadan is blasphemy because it entails belying Allah and the Prophet. However, the one who believes Fasting is an obligation, yet does not perform it (without a valid excuse) does not blaspheme–although his neglecting to fast is an enormous sin.
