The fact that Avshalom was his son should be sufficient reason. In addition, King David was deeply saddened that Avshalom had committed the grave sin of rebelling against him, God's anointed. His tears were a prayer that God should forgive Avshalom (Talmud, Sotah 10b).
He mourned him bitterly, since he (Avshalom) was his (King David's) son, even though he (Avshalom) had attempted to kill him.
His son Absalom.
King David wept for the son that Bathsheba had and for Absalom.
ABSALOM
abimelech
saul
Absalom was King David's son, in the Old Testament.
His son Absalom.
King David wept for the son that Bathsheba had and for Absalom.
ABSALOM
abimelech
Absalom, King David's son, died before he did. Absalom rebelled against his father, leading to a conflict in which he was killed. King David mourned deeply for Absalom's death despite their strained relationship.
King David said this after the death of Absalom in battle.
saul
The oldest from which wife?
Absalom's mother was Maacah, the daughter of Talmai, the king of Geshur. She was one of King David's wives.
David's first-born son was Amnon. Absalom born after Amnon of another David's wife known for his hair. Then came Adoniah and next Salomon. Absalom did revolt but it was Joab, one of the king's general who killed him.
According to Samuel II, chapter 3, verse 3, Absalom was the son of Maacha, who was the daughter of Talmai, king of Geshur. She was one of King David's wives.Sources:absalommaacah