If every act of takwīn itself begins to exist, how did the first takwīn arise? If through another takwīn, that second would require a third, and so on in a regress.
If a takwīn occurs without another takwīn, the premise that each originated takwīn requires a further act has been abandoned. The argument also warns against leaving the world’s origination without a principle that explains it.
This regress argument is directed at the hypothesis of an originated takwīn. It does not, without additional premises, establish an unrestricted verdict on every kind of temporal succession.