They, i.e. the violence and strife last mentioned, Psalms 55:9, go about it; do encompass it, and are as it were the garrison by which they design to defend it. Upon the walls thereof; in the more outward parts, as also in the very midst of it, as it follows. So that all parts were horribly corrupted.
Related Commentaries of Psalms 55:10
Psalms 55:10
10 Day and night they go about it upon the walls thereof: mischief also and sorrow are in the midst of it.