(ذوقوا فتنتكم)
With the assumption of a verbal utterance acting as a circumstantial qualifier (*hal*) for the pronoun in "they are being tried" (*yuftanun*), meaning it is said to them: "Taste your trial," which refers to your punishment prepared for you. Sometimes that which results in punishment, such as disbelief, is called a trial. It is permissible that it is from this category in this context, as if it were said: "Taste your disbelief," meaning the recompense for your disbelief. Alternatively, disbelief may be made synonymous with the punishment itself metaphorically, though this is a view to be considered.
(هذا الذي كنتم به تستعجلون)
This is a sentence consisting of a subject (*mubtada’*) and predicate (*khabar*) falling under the scope of the implied utterance. It means: "This is the punishment which you used to hasten by way of mockery." It is also permissible for "this" (*hadha*) to be a substitute (*badal*) for "your trial," interpreting it as "the punishment." In this, however, there is remoteness.