Does a Muslim pray only twelve rak'ahs as mentioned in the hadith, or does he add to them four rak'ahs before Dhuhr and four after it, according to the hadith: "Whoever prays four rak'ahs before Dhuhr and four after it, Allah will forbid him from the Hellfire"?

It is possible to reconcile the two noble hadiths: "Whoever prays four rak'ahs before Dhuhr and four after it, Allah will forbid him from the Hellfire," and "Whoever prays twelve rak'ahs in a day and night, a house will be built for him in Paradise." Thus, whoever prays four rak'ahs before Dhuhr and four after it has acted upon the first hadith, and has prayed the twelve rak'ahs mentioned in the second hadith with an addition. This addition does not contradict the stated number.