John Calvin Commentary Genesis 37:12

"And his brethren went to feed their father`s flock in Shechem." — Genesis 37:12 (ASV)

And his brethren went. Before Moses discusses the horrible plan of fratricide, he describes Joseph's journey and, through many circumstances, amplifies the atrocity of the crime. Their brother approaches them fulfilling a duty, to make a brotherly inquiry about their well-being. He comes by his father's command and obeys it without reluctance, as is evident from his answer. He searches for them anxiously; and though they had moved, he spares no effort or trouble until he finds them.

Therefore, their cruelty was something more than madness, considering they did not shrink in horror from plotting the death of such a devout and humane brother. We now see that Moses does not relate without purpose that a man met Joseph in his wanderings and told him that his brothers had gone to Dothan. For the greater his diligence in his tireless pursuit, the less excusable were they, by whom he was so unworthily repaid.