What's the Big Deal in This Regard?

This is a hadith in Imam al-Buhari's book and adab al-mufra. One day the Prophet sallallahu alayhi wa sallam said I swear by him in whose hands is my soul if you know what I know You would laugh little and cry a lot. The people began feeling sad and crying So Allah subhanahu wa ta'ala sent you breathe to Muhammad and gave him why hey listen to this Yaa Muhammad lema tukunutur ibaadi Oh Muhammad sallam, why are you creating despair in my servants?