Tafsir Ibn Kathir
15:4 - 15:5

Every Township has its allotted Time

Allah is informing us that He never destroys a township until He has established evidences for it and its allotted time has ended. When the time for a nation's destruction has come, He never delays it, and He never moves its appointed time forward. This was a message and a warning to the people of Makkah, telling them to give up their Shirk, their stubbornness and disbelief for which they deserved to be destroyed.