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

لا يكونُ العَبدُ مؤمناً حتّى‏ يكونَ خائفاً راجِياً، ولا يكونُ خائفاً راجِياً حتّى‏ يكونَ عامِلاً لِما يَخافُ ويَرْجو.

'A servant is not a believer until he is both fearful and hopeful, and he is not fearful and hopeful until he acts in accordance with what he fears and what he hopes for.'

Source: Bihar al-Anwar, v. 70, p. 392, no. 61