It is narrated from Hazrat Abu Dharr (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: O Abu Dharr! Soon there will come some rulers who will not perform the prayer at its appointed time. You should perform the prayer at its appointed time. If you come at a time when the people have already prayed, then you have preserved your prayer, and if they have not prayed, then join them, and this prayer will be a voluntary (nafl) prayer for you.