Hawzah News Agency – Imam Sadiq peace be upon him says:

إنَّ سُوءَ الخُلقِ لَيُفسِدُ العَملَ كما يُفسِدُ الخَلُّ العسَلَ.

'Verily ill nature spoils one's deeds just as vinegar spoils honey.'

Source: al-Kafi, v. 2, p. 321, no. 1