Observe whether there's a cresent moon or not; Fast according Islamic calendar; Follow Prophet Muhammad's teachings; Be patient & persevere even if you cannot physically observe something; Make informed decisions based on your knowledge & understanding of how things work .

This hadith teaches us about the importance of following the Islamic calendar for religious observances such as fasting. When we see the crescent moon in the sky, this marks a new month and thus signals that it is time to begin fasting. When we can no longer see the crescent moon in the sky, this marks an end of a month and thus signals that it is time to stop fasting. If due to cloudy weather or other reasons we are unable to see if there is a crescent moon or not, then we should count thirty days from when we last saw it in order to determine when our fast should begin or end. This hadith also teaches us about patience and perseverance as even if one cannot physically observe something they can still use their knowledge and understanding of how things work in order to make an informed decision on what action they should take next.