ADRIEL (ā'drĭ-ăl, Heb. ’adhrîēl, God is my help). Son of Barzillai the Meholathite, to whom Merab, Saul’s daughter, was given in marriage, though she had been promised to David (1Sam.18.19; 2Sam.21.8). According to 2Sam.21.8 he had five sons, all of whom perished in David’s dreadful and sinful acquiescence in the demand of the Gibeonites for scapegoats. As in the NIV of 2Sam.21.8 the correct form is “Merab,” not “Michal” (as explained in the footnote).

ADRIEL ā’ drĭ əl (עַדְרִיאֵ֥ל, my God is my help). The son of Barzillai, who lived in the Jordan Valley not far S of Bethshean. Saul gave him his daughter Merab, although Saul had promised to give her to David (1 Sam 18:19; 2 Sam 21:8). “Michal” in 2 Samuel 21:8 is a textual error for “Merab.”

International Standard Bible Encyclopedia (1915)

The son of Barzillai the Meholathite, to whom Merab the daughter of King Saul was married when she should have been given to David (1Sa 18:19; 2Sa 21:8). "Michal" in 2Sa 21:8 is a textual error easily accounted for Adriel and Merab had five sons, whom David handed over to the blood vengeance of the men of Gibeon. The name Adriel seems to be Aramaic, the equivalent of the Hebrew name Azriel.