Musnad Ahmad 1153:1557

Yahya ibn Sa'id narrated to us, from Hisham—meaning ibn 'Urwah—from his father, from 'Aishah, that she said: "The Messenger of Allah, peace and blessings of Allah be upon him, only descended at al-Muhassab so that it would be easier for his departure, and it is not a Sunnah. So whoever wishes may descend there, and whoever wishes may not descend there."