The servant abideth not ... - The servant does not, of course, remain forever, or until his death. with his master. If he is disobedient and wicked, the master sells him or turns him away. He is not the heir, and may at any time be expelled from the house of his master. But a son is the heir. He cannot be in this manner cast off or sold. He is privileged with the right of remaining in the family. This takes place in common life. So said the Saviour to the Jews: “You, if you are disobedient and rebellious, may at any time be rejected from being the people of God, and be deprived of your special privileges as a nation. You are in the condition of servants, and unless you are made free by the gospel, and become entitled to the privilege of the sons of God, you will be cast off like an unfaithful slave.” Compare Hebrews 3:5-6.
Abideth not - Remains not, or has not the legal right to remain. He may at any time be rejected or sold.
In the house - In the family of his master.
For ever - During the whole time of his life.
The Son - The heir. He remains, and cannot be sold or cast off.
Ever - Continually. Till the day of his death. This is the privilege of a son, to inherit and dispose of the property.