Tafsir of Al-Waqi'ah 56:4

When the earth will be shaken with a terrible shake. meaning, it is shaken and moved violently over all of its surface and through its depths. Ibn Abbas, Mujahid, Qatadah and others said about Allah's this saying, "Violently shaken.'' Ar-Rabi` bin Anas said, "The earth will be shaken with all that is in it, just as a sifter is shaken with its contents.'' This is like Allah's saying:

إذا زلزلت اﻻرض زلزالها

When the earth is shaken with its earthquake. (99:1) and,

يٲيها الناس اتقوا ربكم إن زلزلة الساعة شء عظيم

O mankind! Have Taqwa of your Lord! Verily, the earthquake of the Hour is a terrible thing. (22:1) Allah said:

وبست الجبال بسا