What is meant by "praying four rak'ahs before Asr" in the hadith: "May Allah have mercy on a person who prays four [rak'ahs] before Asr"?

The hadith indicates the permissibility of praying four rak'ahs after the time for Asr prayer begins and before performing it. This suggests its desirability, not its obligation, and the time for performing it is after the Asr adhan.