Is it permissible, for the purpose of seeking reward, to continue performing four rak'ahs before 'Asr and four after Dhuhr, regarding whose virtues there are weak hadiths?

It is recommended for a Muslim to pray four rak'ahs before Dhuhr and four rak'ahs after it, due to the saying of the Prophet (peace be upon him): "Whoever prays four rak'ahs before Dhuhr and four after it, Allah will forbid him from the Hellfire." It is also recommended to pray four rak'ahs before Asr, due to the saying of the Prophet (peace be upon him): "May Allah have mercy on a person who prays four (rak'ahs) before Asr."