Albert Barnes Commentary 1 Samuel 16:4

"And Samuel did that which Jehovah spake, and came to Beth-lehem. And the elders of the city came to meet him trembling, and said, Comest thou peaceably?" — 1 Samuel 16:4 (ASV)

Trembled - There was evidently something unusual in Samuel’s coming to Bethlehem; and the elders, knowing that Samuel was no longer on friendly terms with Saul, foreboded some evil.