Day and night they go about it, upon the walls thereof - That is, continually. The word “they” in this place probably refers to the violence and strife mentioned in the preceding verse. They are here personified, and they seem to surround the city; to be everywhere moving, even on the very walls. They are like a besieging army. Inside and outside; in the midst of the city and on the walls, there was nothing but violence and strife - conspiracy, rebellion, and crime.
Mischief also and sorrow are in the midst of it - Crime abounded, and the result was anguish or sorrow. This language would well describe the scenes when Absalom rebelled; when the city was filled with conspirators and rebels; and when crime and anguish seemed to prevail in every part of it.