The invention relates to a device (100) for a medical instrument for applying a surgical suture, comprising a release unit (200) and an operating unit (300), said operating unit (300) comprising two pivotable gripper jaws (310,320), each gripper jaw (310, 320) having a needle receptacle (340) and a needle fixation arrangement, said release unit (200) being configured to move the two gripper jaws (310, 320), and the trigger unit (200) also being configured to actuate said needle fixation arrangement.