Smell, in general, has strong influence on humans and animals. Many people (and animals) even continue to remember a certain smell throughout their lives. However, people who have smelly breath often face a lot of problems in their daily interactions. During a conversation, the other person will try to distance themselves or hold their breath. For people who have bad breath problem, surely they will feel embarrassed.
Generally, bad breath is caused by food, such as garlic, bitter beans (petai), drinking alcohol and smoking. It can also be caused by dry mouth or due to a disease or infection. In order to reduce bad breath, it is important to maintain good oral hygiene every day.
It is permissible to eat the food mentioned above (except for alcohol) as long as we clean our mouth immediately. Otherwise, our breath might be a bother to other people, especially during our prayers in a saf(row) or when we communicate with other people. Their concentration and attention might be affected. Thus, the Prophet (peace and blessings be upon him) stressed that we have to clean, not only our bodies, clothes and the place of prayer but also the smell of our mouths.