I saw the Messenger of Allah ﷺ praying and a sound came from his breast like the rumbling of a mill owing to weeping.  

رَأَيْتُ رَسُولَ اللَّهِ ﷺ يُصَلِّي وَفِي صَدْرِهِ أَزِيزٌ كَأَزِيزِ الرَّحَى مِنَ الْبُكَاءِ ﷺ