New Defender's Study Bible Notes
2:17 Abishag the Shunammite. This request was a gratuitous insult from Adonijah to his younger brother Solomon, in effect assuming the role of “brother” to his own father. Abishag was David’s last wife before he died, and had no children, so Adonijah would thus be arrogating that role to himself. Even if this were not a part of his thinking, such a relationship would clearly be an incestuous violation of the divine law (Leviticus 18:6-8,29), subject to capital punishment.