Al-Fudayl bin 'Iyaad said:

Since twenty years I have been seeking a companion who when angry [with me], does not lie upon me.

Note: A state of anger and discontent (with a person) predisposes a person to incline towards not being truthful and to lie. Hence, the cure from this is to become pleased for Allaah's sake only and to become angry for Allaah's sake only, and to love for Allaah's sake only and to hate for Allaah's sake only, and to strengthen one's knowledge and faith in the affair of al-qadaa wal-qadar.

In Mausoo'ah Ibn Abi al-Dunyaa of Ibn Abi al-Dunyaa (7/542) through Hayaat al-Salaf of Ahmad al-Tayyaar.
Translated by Abu Iyaad (@abuiyaadsp)