I prayed Asr and then heard the adhan, is my prayer valid or should it be repeated (Maliki school)?

Summary of the fatwa: If someone prays before confirming the entrance of the time, their prayer is not valid even if it turns out that they prayed within the correct time. If they pray after the time has entered, being certain, their prayer is valid, and it is recommended to repeat it with the congregation to receive its virtue, except for Maghrib and Isha prayers. However, if someone prays Maghrib or Isha alone and has performed Witr, and then finds a congregation, it is not prescribed for them to repeat the prayer in the Maliki school of thought. The Asr prayer time begins after the end of the Dhuhr time until the shadow of everything becomes twice its length.