﴿ لَتَرْكَبُنَّ طَبَقًا عَن طَبَقٍۢ ﴾

“[even thus, O men,] are you bound to move; onward from stage to stage.”

you will surely journey tarkabunna is actually tarkabūnanna but the nūn of the indicative has been omitted because of two identical letters following one another and the wāw is omitted because of two unvocalised consonants coming together from stage to stage state after state namely death then life then what comes afterwards of the states at the Resurrection.