Ан-Назиат 79:2

The second quality of the angels:

وَالنَّاشِطَاتِ نَشْطًا (and by those [ angels ] who untie the knot [ of the souls of the believers ] smoothly, [ 2] ' The word nashitat is derived from nasht and it means 'to untie the knot'. This signifies 'to untie the knot of something which contains water or air, so that it may be released easily'. This is metaphor for drawing out the souls of the believers gently, unlike the souls of the infidels which are plucked out harshly. In this case too, the adverb 'smoothly' refers to the spiritual smoothness, and not to the physical experience. Sometimes, it happens that there is a delay at the time of death of a righteous believer. This may not be suspected to mean that he is undergoing some sort of suffering, although physically it may seem so. When the soul of an infidel is extracted, the entire scene of the punishment of barzakh comes in front of him. It is frightened by it, disperses throughout the body and tries to hide or escape. The angels forcefully extract the soul just as wet wool wrapped around a skewer is forcefully removed. When the soul of a believer is extracted, on the other hand, the reward, the blessings and the welcome news of the barzakh come in front of him.