I say, and with Allah's success: It was reported in the hadith from Umm Habiba, may Allah be pleased with her, that the Prophet, peace be upon him, said: "Whoever prays twelve rak'ahs in a day, Allah will build for him a house in Paradise: four before Dhuhr, two after it, two before Asr, two after Maghrib, and two before Fajr." Al-Mustadrak 1: 456, and it was authenticated, and Sunan al-Tirmidhi 2: 274, and he said: it is good and authentic, and others. Thus, the Sunnah of the four before Dhuhr was established, then there was a difference in ijtihad regarding whether to pray them together or two by two. Abu Hanifa's ijtihad was to pray four consecutively because it is a longer time of tahreem (the state of being in prayer), which would be more arduous and of greater virtue. This was supported by the hadith of Aisha, may Allah be pleased with her, who said: "The Messenger of Allah, peace be upon him, did not increase in Ramadan or in other months beyond eleven rak'ahs: he would pray four, so do not ask about their beauty and length, then he would pray four, so do not ask about their beauty and length, then he would pray three." Sahih Muslim 1: 509, and Sahih Bukhari 1: 385, and Allah knows best.