Sunan Abi Dawud, Hadith 2003

Narrated 'Aishah: The Messenger of Allah alighted at al-Muhassab so that it might be easier for him to proceed (to Medina). It is not a sunnah (i.e. a rite of Hajj). Anyone who desires may alight there, and anyone who does not want may not alight.

حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ إِنَّمَا نَزَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْمُحَصَّبَ لِيَكُونَ أَسْمَحَ لِخُرُوجِهِ وَلَيْسَ بِسُنَّةٍ فَمَنْ شَاءَ نَزَلَهُ وَمَنْ شَاءَ لَمْ يَنْزِلْهُ ‏.‏

sunnah.com

also referenced under: Hadith 2008 (DarusSalam)