References – MN 83: About King Maghadeva 
“What is hasituppāda citta—consciousness producing mirth—that is the Buddha’s smile?” Answered by Ajahn Pasanno. [Humor ] [Buddha/Biography] // [Teaching Dhamma]
Suttas: MN 81; MN 83; AN 5.180: Examples of the Buddha’s smile.
Sutta: MN 12.58: “You might think that the jujube fruit was bigger in those days...” [Ascetic practices]
Sutta: SN 17.5: A dung beetle gloats about his pile. [Gain and loss] [Fame and disrepute] [Similes] [Monastic life]