Hawzah News Agency – Imam al-Sadiq (AS), when asked what consolidates a servant's faith, replied,

الّذي يُثَبّتُهُ فيهِ الوَرَعُ، والّذي يُخْرِجُهُ مِنهُ الطَّمَعُ.

'The thing that consolidates it in him is piety, and that which takes him out of it [i.e. faith] is greed.'

Source: al-Khisal, p. 9, no. 29