Perform wudu when there's an odor or sound present.

This hadith teaches us about the importance of performing ablution, which is a ritual washing of certain parts of the body before prayer. According to this hadith, it is only necessary to perform ablution if there is an odor or sound present. This means that if one has not performed any activities that would cause them to become unclean, such as going to the bathroom or passing gas, then they do not need to perform ablution before prayer. This hadith also teaches us about cleanliness and how important it is in our religion. It reminds us that we should always strive for cleanliness and purity in our lives so that we can be closer to Allah and His Messenger Muhammad (PBUH).