Staying at Al-Mahassab is not one of the ceremonies (of Hajj), but Al-Mahassab is a place where Messenger of Allah ﷺ camped (during his Hajjat-al-Wida).  

عَنِ ابْنِ عَبَّاسٍ ؓ لَيْسَ التَّحْصِيبُ بِشَىْءٍ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللَّهِ ﷺ  

Halt at Muhassab is not something (significant from the point of view of the Shari'ah). It is a place of halt where Messenger of Allah (way peace be upon him) halted.  

لَيْسَ التَّحْصِيبُ بِشَىْءٍ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللَّهِ ﷺ  

"At-Tahsib is nothing, it is only a place that the Messenger of Allah camped at."  

لَيْسَ التَّحْصِيبُ بِشَيْءٍ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللَّهِ ﷺ  

"At-Tahsib is nothing, it is only a place that the Messenger of Allah camped at." (Using translation from Tirmidhī 922)  

«لَيْسَ الْمُحَصَّبُ شَيْءٌ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللهِ ﷺ»  

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)   

«الْمُحَصَّبُ لَيْسَ بِسُنَّةٍ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللهِ ﷺ لِيَكُونَ أَسْمَحَ لِخُرُوجِهِ»  

Halt at Muhassab is not something (significant from the point of view of the Shari'ah). It is a place of halt where Messenger of Allah (way peace be upon him) halted. (Using translation from Muslim 1312)   

«إِنَّ الْمُحَصَّبُ لَيْسَ بِشَيْءٍ إِنَّمَا هُوَ مَنْزِلٌ نَزَلَهُ رَسُولُ اللهِ ﷺ»