Jest not at another's infirmities.

Do not turn another person's weakness, illness, limitation, or misfortune into a joke. The saying condemns amusement gained by exposing vulnerabilities that may already cause the other person pain or embarrassment.

It calls for restraint and sympathy rather than ridicule. Here, “infirmities” may mean human weaknesses generally as well as illness or physical frailty; the saying concerns mockery of vulnerability, not the avoidance of legitimate criticism of harmful conduct.

Use this as a moral reminder when teasing targets a person's physical condition, emotional vulnerability, limited ability, or personal hardship. Its formal wording suits reflective or admonitory discussion more than casual banter, and it should not be used to dismiss justified criticism of harmful behavior.