Ezekiel 33:9

“Nevertheless if you warn the wicked of his way, to turn from it, and he does not turn from his way, he will die in his iniquity, but you will have delivered your life.”

But many individuals who are warned will not listen. They will refuse to change their ways. They will therefore die in their sin. But the watchman will have ensured that he is guiltless because he has warned them. No blame can then be laid at his door.