瑜伽論記 4.54

4.54

笑者：謂如有一，或因開論，或因合論等者，顯說話名開論，隱密約喻說話合之令解名合論，開口而笑名現齒，喉中出聲名啞啞。

Regarding laughing: 'that is, like someone who, whether because of an open exposition, or because of a synthesized exposition...', speaking explicitly is called 'an open exposition', while speaking covertly through parables and synthesizing them to make someone understand is called 'a synthesized exposition'. Opening the mouth to laugh is called 'showing the teeth', and making a sound in the throat is called 'chortling'.