The first point is the description of fasting as a means of protection, without specifying what it protects from. However, since it is an act of worship undertaken purely for God's sake, it is understood that it is a means of protecting oneself from hell. Because a fasting person feels physically weaker, he is less prone to indulge in sin. As the feeling of fasting is present in his mind all the time, he is mentally keen to do nothing that incurs God's displeasure. Hence, it is a protection from all types of disobedience to God.
The next point is that whoever is fasting must never get involved in a verbal or physical quarrel. He must remind himself that he is on a fast, and such fast requires him to observe the best rules of propriety in all situations. Should anyone provoke him, he should turn away and say: I am fasting; I am fasting. The phrase is repeated twice so as to allow it to have its certain effect of calming him down. Scholars have considered whether this should be said aloud or to oneself. There are different opinions on this, but the view that seems to be more in line with the values of fasting is that he says it aloud during Ramadan, but says it to oneself in secret if his fast is voluntary. The reason is that other people do not know that he is volunteering to fast. He should keep that as a private matter between himself and God. Therefore, he does not say it aloud so that it may not be interpreted as boasting.
Another version of this Hadith adds that when you are fasting and someone provokes you into a quarrel, whether verbal or physical, you are also recommended to sit down if you are standing, and to recline if you are seated. The change of position will add to the calming effect of saying, I am fasting.
Some people's mouth start to smell when they go several hours without eating or drinking anything. A fasting person goes without food or drink for at least 11 hours if the fast is in the middle of winter. The length of fasting extends to 18 hours or even longer in northern areas in the summer, as it is the case these days. The Prophet reassures us that we must not worry about that. If one wants to brush one's teeth during the day of fasting, one should not use toothpaste. A toothstick or a dry toothbrush is good enough. However, God considers that the mouth smell of a fasting person is more pleasant than the smell of musk.
Finally, the Hadith tells us that a fasting person has two occasions to rejoice. The first is at the time of ending the fast. Having gone for a full day of fasting in obedience to God, he is pleased that God has enabled him to do so without much difficulty. He knows that his record of good deeds has been credited with a new highly valuable entry. The other occasion is on the Day of Judgment when people's deeds are reckoned. He will then receive the reward of fasting, and when he learns what it is like, he is most pleased.