C. F. Keil and Franz Delitzsch on Genesis 37:21-24

Gen 37:21-24 Reuben, who was the eldest son, and therefore specially responsible for his younger brother, opposed this murderous proposal. He dissuaded his brethren from killing Joseph (נפשׁ פ הכּה ), and advised them to throw him “into this pit in the desert,” i.e., into a dry pit that was near. As Joseph would inevitably perish even in that pit, their malice was satisfied; but Reuben intended to take Joseph out again, and restore him to his father. As soon, therefore, as Joseph arrived, they took off his coat with sleeves and threw him into the pit, which happened to be dry.