Genesis 30:4-8

So she gave him her slave Bilhah as a wife, and Jacob had relations with her.

Bilhah conceived and bore Jacob a son.

Then Rachel said, “God has vindicated me, and has indeed heard my voice and has given me a son.” Therefore she named him Dan.

And Rachel’s slave Bilhah conceived again and bore Jacob a second son.

So Rachel said, “With mighty wrestling I have wrestled with my sister, and I have indeed prevailed.” And she named him Naphtali.