وَنُؤْمِنُ بِمَلَكِ الْمَوْتِ الْمُوَكَّلِ بِقَبْضِ أَرْوَاحِ الْعَالَمِينَ
We believe in the Angel of Death, entrusted with taking the souls of the worlds.
Malak al-mawt means the Angel of Death. The taking of souls happens under Allah's command and the responsibility He has assigned. Death does not occur by an angel's independent will; the angels obey their Lord.