It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) used to stand (in prayer) in the first two rak'ahs of Zuhr for a duration equal to thirty verses, and in the last two rak'ahs, he would stand for half of that. In the first two rak'ahs of 'Asr, he would stand for the same duration as the last two rak'ahs of Zuhr, and in the last two rak'ahs of 'Asr, he would stand for half of that.