Twins are born, sons of Yehuda and Tamar. The Torah gets into the seemingly unnecessary nitty gritty details of the story of their birth. Yet, upon deeper reflection, their names, identities and their future descendants are all represented in this story.

Sources:

Sefer Yehoshua Perek 7

Gemara Sanhedrin 43 B and 44 A

Gemara Yevamos 77 B

Yalkut Meam Loez on Megillas Rus Perek 4 Possuk 12

Likkutei Amarim Tanya Perek 15

Sefer Gilgulei Neshamos Chapter 102 (Ma'areches Ayin - Achan)