Musnad Ahmad 1153:1922

Ibn Numayr narrated to us, he said: Hisham narrated to us, from his father, from Aisha, she said: I did not see the Messenger of Allah, peace and blessings of Allah be upon him, reciting in any of the night prayers while sitting, until he reached an advanced age. Then he would sit and recite, until when thirty or forty verses of the surah remained, he would stand and recite them, then he would bow.