'Offspring' in the Bible

They brought the head of Ish-bosheth to David at Hebron, and said to the king, “Look, the head of Ish-bosheth the son of Saul, your enemy, who sought your life; thus the Lord has granted my lord the king vengeance this day on Saul and on his descendants.”

When your days are fulfilled and you lie down [in death] with your fathers (ancestors), I will raise up your descendant after you, who shall be born to you, and I will establish his kingdom.

“He is a tower of salvation and great deliverance to His king,And shows lovingkindness to His anointed,To David and his offspring forever.”