[nmh]

That is not true.

Sarah and Abraham were married. Hagar never was the WIFE of Abraham, hence Isaac is the LEGITMATE son - between tow married people. NEVER is Hagar referred to as Abrahams's wife because she is not - she is just a maid to Sarah.

[muawiyah]

We are discussing the legitimacy of the offspring in what was clearly a polygamous society. That has absolutely nothing to do with the marriage a man might have made with one, two or a dozen women, or whether or not it was considered appropriate to share one's handmaiden for purposes of procreation (only, of course)!

The children were Abram's, and that's all that counted in that society at that time. It is inappropriate to read modern understandings into events in his life.