Matthew Henry on 2 Samuel 19:31-39

Barzillai thought he had done himself honour in doing the king any service. Thus, when the saints shall be called to inherit the kingdom, they will be amazed at the recompence being so very far beyond the service, Mt 25:37. A good man would not go any where to be burdensome; or, will rather be so to his own house than to another's. It is good for all, but especially becomes old people, to think and speak much of dying. The grave is ready for me, let me go and get ready for it.