Rebellion 13:1–20:26: Although the Lord did not explicitly forbid polygamy, the story recounted in 13:1–14 illustrates why multiple marriages are unwise. Hatred and jealousy among half brothers was a constant problem and sometimes led to murder (cf. Judg. 9:5), especially when one’s own sister is violated (cf. Genesis 34). It is unlikely that the heart of the matter in this story is an unlawful relationship: while Leviticus 18:9 and 20:17 forbid sexual relations with one’s sister (half sister or not), taking a “wifster” (wife-sister) was commonplace if not encouraged, particularly in royal families. (This ensured, for instance, that any claims to the throne were kept within the family.) This episode probably reflects a power play by Amnon, perhaps to keep another pretender to the throne in…