The Zabur is the holy book attributed to Prophet David by God, just as Prophet Moses (Musa) got the Tawrat (Torah), Prophet Jesus (Isa) got the Injil (Gospel) and Prophet Muhammad (Muḥammad ibn ʿAbd Allāh ibn ʿAbd al-Muṭṭalib ibn Hāshim) received the Quran.
Your Lord knows whoever is in the heavens and the earth.