What was the relationship between Leah and Judah?
Leah was the mother of Judah. When he was born, she said she would give praise to the Lord, and so she named him Judah. Genesis 29:35
What the Bible says
Genesis 29:35
The fourth time she conceived and bore a son, and said: now will I praise the Lord: and for this she called him Juda. And she left bearing.
Douay-Rheims Bible (Challoner revision), public domain.