Abu Basra al-Ghifari said

Allah's Messenger ﷺ led us in the afternoon prayer at al-Mukhammas and said, “This is a prayer which was proposed to your predecessors, but they neglected it. Everyone who keeps observing it will have a double reward, but there is no prayer after it till ash-shahid rises.” Ash-shahid is the star.* * No particular star is intended. The meaning is that the prayer should be observed when stars become visible. Muslim transmitted it.