Abu al-Aliyah relates: Thirty of the Companions gathered and said: "As for the prayers in which the Prophet (peace and blessings be upon him) used to recite aloud, we know them; and as for those in which he did not recite aloud, we will not draw an analogy for them from those in which he recited aloud." The narrator relates: Those Companions agreed on this, and not even two of them differed, that in the Zuhr prayer the Prophet (peace and blessings be upon him) used to recite about thirty verses in each of the first two rak'ahs, and in the last two rak'ahs half of that; and in the Asr prayer he used to recite half of what he recited in the first two rak'ahs of Zuhr, and in the last two rak'ahs half of the amount of the last two rak'ahs of Zuhr.
Ahmad recorded it; its chain contains Abd al-Rahman bin Abdullah al-Mas'udi, who is thiqah (trustworthy) but suffered from mental deterioration (ikhtilat). It is said that Yazid bin Harun heard from him during his deterioration. And Allah knows best.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2676