This Sahaabi is Abu Moosa al-Ash’ari.
Al-Bukhaari narrated from Burayd ibn ‘Abd-Allaah ibn Abi Burdah from his grandfather from Abu Moosa (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “O Abu Moosa, you have been given one of the mizmaar of the family of Dawood.” (Fadaa’il al-Qur’aan, 4660). Ibn Hajar said: “What is meant by mizmaar is a beautiful voice. The original meaning is a musical instrument and the word is applied to the voice because it resembles it.
Abu Moosa was one of those who memorized the entire Qur’aan. The Prophet (peace and blessings of Allaah be upon him) sent him to Yemen as a qaadi (judge) and teacher. He is well known for reading the Qur’aan a great deal, and for standing in prayer at night (qiyaam al-layl). May Allaah be pleased with him and reward him, and may He gather us with him, together with the Prophets, the speakers of truth, the martyrs and the righteous.