Charles Ellicott Commentary Exodus 21:4

"If his master give him a wife and she bear him sons or daughters; the wife and her children shall be her master`s, and he shall go out by himself." — Exodus 21:4 (ASV)

If his master have given him a wife.—If, however, the Hebrew slave, being previously unmarried, had been allowed by his master to take to wife one of his female slaves, then, when the husband claimed his freedom the wife could not claim hers. Both she and her children remained in the slave condition.