Hadith: We used to estimate the time that the Messenger of Allah (may Allah's peace and blessings be upon him) would stand when performing the Zhuhr and the ‘Asr prayers. We estimated that the time he stood in the first two Rak‘ahs of the Zhuhr prayer as the being the time taken to recite Sūrat As-Sajdah and it would be half of that time in the last two Rak‘ahs

عن أبي سعيد الخدري رضي الله عنه قال: «كنا نَحْزِرُ قيام رسول الله صلى الله عليه وسلم في الظهر والعصر فَحَزَرْنَا قيامه في الركعتين الأُولَيَيْنِ من الظهر قَدْرَ قراءة الم تنزيل السجدة وَحَزَرْنَا قيامه في الأُخْرَيَيْنِ قدر النصف من ذلك، وَحَزَرْنَا قيامه في الركعتين الأوليين من العصر على قدر قيامه في الأُخْرَيَيْنِ من الظهر وفي الأخريين من العصر على النصف من ذلك» ولم يذكر أبو بكر في روايته: الم تنزيل وقال: قدر ثلاثين آية.
[صحيح] - [رواه مسلم]

Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported: We used to estimate the time that the Messenger of Allah (may Allah's peace and blessings be upon him) would stand when performing the Zhuhr and the ‘Asr prayers. We estimated that the time he stood in the first two Rak‘ahs of the Zhuhr prayer as the being the time taken to recite Sūrat As-Sajdah and it would be half of that time in the last two Rak‘ahs. We also estimated the time he stood in the first two Rak‘ahs of the ‘Asr prayer as being the same as the time he stood in the last two Rak‘ahs of the Zhuhr prayer and half of that time in the last two Rak‘ahs of the ‘Asr prayer." Abu Bakr did not mention Sūrat As-Sajdah in his narration, instead he said: “the time taken to recite thirty verses.”
[Authentic hadith] - [Narrated by Muslim]

Explanation

This noble Hadīth clarifies the duration of standing in the Zhuhr and ‘Asr prayers. The duration of standing in the first two Rak‘ahs of the Zhuhr prayer is equal to the duration of reciting thirty verses; the time taken to recite Sūrat As-Sajdah, and the last two Rak‘ahs take about half that time; the time taken to recite fifteen verses. The ‘Asr prayer is shorter than the Zhuhr prayer, as the first two Rak‘ahs last long enough to recite fifteen verses and the last two Rak‘ahs take half that time; the time taken to recite seven to eight verses.