Hawzah News Agency – The commander of the faithful, Imam Ali peace be upon him says:

ماجَفَّتِ الدُّموعُ إلّا لِقَسوةِ القُلوبِ، وما قَسَتِ القُلوبُ إلّا لكَثرَةِ الذُّنوبِ.

'Tears only dry up [i.e. fail to flow] as a result of hardness of the heart, and the hearts only harden as a result of frequent sinning.'

Source: Ilal al-Sharai, p. 81, no. 1