Hawzah News Agency – The merciful prophet of Islam (pbuh) says:

خَصلَتانِ ليسَ فَوقَهُما مِنَ البِرِّ شَي‏ءٌ: الإيمانُ بِاللَّه والنَّفعُ لِعبادِ اللَّهِ، وخَصلَتانِ لَيسَ فَوقَهُما مِنَ الشَّرِّ شَي‏ءٌ: الشِّركُ بِاللَّهِ والضُّرُّ لِعِبادِ اللَّه.

'There are two virtues unexcelled by anything better: faith in Allah, and being of benefit to Allah's servants. And there are two iniquities unsurpassed by anything worse: associating something with Allah, and causing harm to Allah's servants.'

Source: Bihar al-Anwar, v. 77, p. 137, no. 2