Pray with others when they are already leading prayers .

This hadith speaks about the importance of praying in a group at the mosque. It tells us that when we pray with others in congregation at the mosque, we will receive an equivalent reward for our prayer as if we were to pray alone at home. This shows us how important it is for Muslims to come together and pray as one community and how Allah rewards those who do so. It also teaches us that even if we are late for prayer and find that someone else has already started praying, it is still beneficial for us to join them and complete our prayer with them.