Jamieson, Fausset and Brown on Genesis 37:29-30

29-30. Reuben returned unto the pit--He seems to have designedly taken a circuitous route, with a view of secretly rescuing the poor lad from a lingering death by starvation. His intentions were excellent, and his feelings no doubt painfully lacerated when he discovered what had been done in his absence. But the thing was of God, who had designed that Joseph's deliverance should be accomplished by other means than his.