The goal of fasting is to achieve Taqwa - fear and love for Allah.
Allah said:
يَا أَيُّهَا الَّذِينَ آمَنُواْ كُتِبَ عَلَيْكُمُ الصِّيَامُ كَمَا كُتِبَ عَلَى الَّذِينَ مِن قَبْلِكُمْ لَعَلَّكُمْ تَتَّقُونَ
O you who believe! Observing saum (the fasting) is prescribed for you as it was prescribed for those before you, that you may become the Muttaqoon (pious). Al Baqarah 2:183
The Prophet Muhammad sallallahu alaihi wa sallama said:
"Perhaps the fasting person gets nothing from his fast except hunger. And perhaps the praying person [at night during Ramadan] gets nothing from his standing [in prayer] except sleeplessness"
Recorded by Ibn Maajah. Declared Sahih by al Albani in Saheeh al Jaami vol. 1 pg. 656.
The fast is meant to be a period of training and development of Taqwa (God-consciousness). IF a person does not abstain from forbidden acts during that time of fasting, then he is actually not receiving or enacting the proper type of training. Hence, the act itself becomes nothing more than a burden and hardship on the person without any beneficial outcome in this life or, possibly, in the Hereafter.
"The goal of fasting is not thirst, and hunger. The goal of fasting is the overcoming of one's desires and defeating the base desires of the soul."
Al Baidhaawi, quoted by IBn Hajr in Fath al Baari vol. 4 p. 117
"The purpose of fasting is that the spirit of man was released from the clutches of desires and moderation prevailed in his carnal self, and, through it, he realizsed the goal of purification and everlasting felicity. It is aimed at curtailing the intensity of desire and lust by means of hunger and thirst, at inducing man to realize how many were there in the world like him who had to go even without a small quantity of food, at making it difficult for the Devil to deceive him, and at restraining his organs from turning towards things in which there was the loss of both worlds. Fasting, thus, is the bridle of the God-fearing, the shiled of the crusaders and the discipline of the virtuous."
Ibn al Qayyim, quoted in Abul Hasan Ali Nadwi, the four Pillars, p. 173.
"While you are fasting, let your hearing, sight and tongue also abstain from lying and the forbidden. Avoid harming your neighbor. You should have calmness and tranquility on the day of your fast. Do not let the day of your fast and the day you break your fast be the same"
Jaabir quoted by Ibn Rajb in Lataaif p. 292
Don't let Ramadan become a festival where one eats and party all night and sleep all day. You can see people who do this dont change from year to year. One of the acceptance of good deeds is that the person is guided to follow up those good deeds with additional good deeds. Everyone should make an effort to change during the month of Ramadan.
Note:
These study notes were taken from Jamaluddin Zaraboso' Purification of the Soul.
