Hawzah News Agency – Imam al-Askari peace be upon him says:

لا تُمارِ فيَذهَبَ بَهاؤكَ، ولاتُمازِحْ فيُجتَرأَ علَيكَ.

'Do not dispute lest your splendour fade, and do not joke lest people feel defiant towards you.'

Source: Tuhaf al-Uqul, p. 486