Removing the sorrow of a believer

 من فَرَّجَ مِن مُؤمِنٍ، فَرَّجَ اللّه ُ عَن قَلبِهِ یَومَ القِیامَهِ

Imam Reza (AS): Whoever removes the sorrow of a believer, God will remove sorrow from their heart on the Day of Judgment.