Saʿīd is to say that Abu Qatādah’s report reflects the Prophet’s regular practice, namely, to make the first rakʿah longer than the second, whereas Abu Saʿīd al-Khudrī’s report describes occasions when the Prophet deviated from that rule. Thus both ways are permissible and both ḥadiths may be followed, though the basic norm remains what is stated in Abu Qatādah’s report: the first rakʿah is lengthened over the second.
Likewise, the prevailing sunnah is to make the Dhuhr prayer longer than ʿAsr, both in recitation and in physical actions.
3 – It is recommended to prolong the recitation and motions of Dhuhr more than those of ʿAsr.
4 – The reason Dhuhr is lengthened in comparison to ʿAsr may lie in the timing: the window for Dhuhr is expansive, whereas ʿAsr is followed by the yellowing of the sun, the time of necessity.
5 – Shaykh al-Islam said: It is commendable to make the first rakʿah of every prayer longer than the second, to extend the first two rakʿahs and shorten the last two; the majority of jurists base this on the present ḥadith.
6 – This ḥadith also supports the position that the worshipper is not confined to al-Fātiḥah alone in the last two rakʿahs of Dhuhr and ʿAsr. Those final rakʿahs of Dhuhr were half the length of the first two, even though the Prophet recited Sūrah al-Sajdah, which begins, “Alif-Lām-Mīm. The revelation….” Authentic reports do state that he sometimes limited himself to al-Fātiḥah in the last two rakʿahs of Dhuhr and ʿAsr. The reconciliation is that he did both at different times, making each permissible. All of this shows that he occasionally recited something in addition to al-Fātiḥah in those rakʿahs. As for reciting after al-Fātiḥah in the first two rakʿahs of Dhuhr and the first two of ʿAsr, that is well known and unanimously accepted.