The Messenger of Allah ﷺ 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. (Using translation from Abū Dāʾūd 2008)
أَنَّهَا قَالَتْ إِنَّمَا نَزَلَ رَسُولُ اللهِ ﷺ الْمُحَصَّبَ لِيَكُونَ أَسْمَحَ لِخُرُوجِهِ وَلَيْسَ بِسُنَّةٍ فَمَنْ شَاءَ نَزَلَهُ وَمَنْ شَاءَ لَمْ يَنْزِلْهُ