When he maketh inquisition for blood— To make inquisition for blood, as we hinted on Psalms 5 is not to inquire after blood spilled, but to sit as inquisitor or judge on all capital crimes, where the blood of the offender is due to justice. Them, refers to the humble or afflicted, who follow after, and whose cry or supplication is contained in the two next verses.
Related Commentaries of Psalms 9:12
Psalms 9:12
12 When he maketh inquisition for blood, he remembereth them: he forgetteth not the cry of the humble.c