Galatians 4:1

What I mean is this. As long as an heir is under age, there is no difference between him and a servant, though he is lord of all the property;

Galatians 4:23

but while the son of the slave-woman was born by the flesh, the son of the free-woman was born by the promise.

Galatians 4:29

but just as in the old days the son born by the flesh persecuted the son born by the Spirit, so it is still to-day.

Treasury of Scripture Knowledge

Summary

Now I say, That the heir, as long as he is a child, differeth nothing from a servant, though he be lord of all;

Bible References

That

Galatians 4:23
but while the son of the slave-woman was born by the flesh, the son of the free-woman was born by the promise.