From Sahih Muslim (Hadith 3168):
Nafi' reported that Ibn 'Umar regarded halt at Muhassab as Sunnah (of the Holy Prophet) and observed the noon prayer on Yaum al-Nafr at that place. Nafi' said:Allah's Messenger (ﷺ) halted at Muhassab and the Caliphs did the same after him
Reference: Muslim 3168