The answer is: Samuel

1 Samuel 15:32-33 - Samuel completed the job that Saul failed to do

In the tale of Saul and Agag, we find not just a clash of swords but a profound narrative highlighting obedience and leadership. When God instructed Saul to utterly destroy the Amalekites, it wasn’t simply He wanted their defeat; it was about the importance of following directives wholeheartedly. Saul’s failure to finish the task by sparing Agag, their king, ultimately paved the way for further conflict, showcasing the consequences of half-measures in leadership.

Samuel’s dramatic confrontation with Agag—a moment where he fulfills the allegiance to God’s command—is especially significant. You might think, “Who is this Samuel, anyway?” Samuel was more than just a prophet; he served as a bridge between the time of the judges and the monarchy. When he takes it upon himself to execute Agag, it’s a bold move combining deep conviction and personal responsibility for the actions of leaders.

Interestingly, this act of Samuel serves as a parallel in the Bible with the role of spiritual guidance over governance, underlining the principle that right ambience and strong principles underpin leadership. Quick fun fact: the name "Agag" has become almost synonymous with wickedness in biblical literature, symbolizing an eternally significant archetype of opposition to Samuel's (and by extension God's) peacekeeping.

Samuel’s actions reflect an unwavering commitment to principle over personal affections, reminding us that sometimes tough decisions must be made for higher purposes—and sometimes, fulfilling these hard calls involves deeply personal sacrifices.