Be mindful when you pray; Join your prayers with others whenever possible; Pay attention while you pray; Be aware of your actions during prayer; Strive for congregational prayer whenever possible.

This hadith highlights the importance of joining prayers with others and praying in congregation. It also shows that it is important to be mindful of our actions and to be aware of what we are doing when we are praying. The Prophet asked the man which prayer was his because he wanted to make sure that he was aware of what he was doing and that he knew which prayer counted as his own. This teaches us to be mindful when we pray and not just go through the motions without paying attention or thinking about what we are doing. We should also strive to join our prayers with others whenever possible as this increases our reward from Allah SWT for each prayer we perform.