Descendant of "Beis Dovid"

...The Baal haHillulo Horav Levi Yitzchok is a descendant of Dovid, as is well known that he was a seventh generation from the Alter Rebbe, who was a seventh generation from the Maharal of Prague – and the Maharal traced his lineage to Dovid.

This is also related to what it says in Gemmara (Talmud Taanis 26a), that on the 20th of Av (the day of the Hillulo-yahrtzeit) a family from the house of Dovid offered the korban eitzim (wood offering) in the Beis HaMikdash.