Strive to fulfill religious obligations even when they are not mandatory .

This hadith is about the Prophet Muhammad's practice of performing twelve Rak'ah of Salat during the day time if he missed his optional night Salat, known as Tahajjud. This shows us that even though it was an optional prayer, it was important to him and he made sure to make up for it in some way. It also teaches us that we should strive to fulfill our religious obligations even when they are not mandatory. We should also remember that Allah is always watching and will reward us for our efforts.