What's the name of the hand that retracts into the sleeve?

The action of retracting your hand into your sleeve is called standby.

Stand by and watch, China idiom, put your hand in your sleeve. Metaphor means that people stay out of it and don't help others. More refers to seeing others in trouble and not helping others.

The origin of the idiom: Tang Hanyu's "Sacrifice to Liu Zi Hou Wen": "If you are not refined, you will be ashamed of blood. A skilled craftsman will shrink his sleeves on the sidelines."

Example:

1, and stand by and watch.

In this case, no one will stand idly by.

The situation is so critical that no one will stand idly by.

My uncle said that he would never stand by.

Compared with those who stand by, those who stand by are worse. Because he is a coward.