Indeed good actions are a light in the heart, a strengthening for the body, a glow on the face, a cause for extensive provisions and love in the hearts of the creation.  Indeed bad actions are a darkness in the heart, a blackness on the face, a weakness for the body, a cause for decrease in provisions and hatred in the hearts of the creation.

—Ibn Abbas

(mentioned by Ibn al-Qayyim in al-Jawab ak-Kafi)

(Read on pg 61, Ibn Taymiyyah, Disease of the Hearts and Their Cures. Daar us-Sunnah Publishers. UK: 2006.)