In the Talmud, Megillah 14b, it mentions towards the end1 that Joshua married Rachav and that Joshua never had sons, but only daughters:
דאיגיירא ונסבה יהושע ומי הוו ליה זרעא ליהושע והכתיב (דברי הימים א ז, כז) נון בנו יהושע בנו בני לא הוו ליה בנחן הוו ליה
Here's a translation:
"That [Rahab] became a convert and she married Joshua. But did Joshua have any offspring? And it isn't written (1 Chronicles 7:27) "Nun his son, Joshua his son"? He did not have sons, but he did have daughters." - Megillah 14b
But in Matthew Chapter 1, it says that Rahab married a certain Salmon. Who is this Salmon, and where did the New Testament authors get that he married Rahab? Is there a reference somewhere within the "Old Testament?"
1 If you read the actual reference I'm making, it's one rabbi's opinion (Rabbi Nachman) on Joshua marrying Rahab.