4:15 Gilgal. This important Israelite sanctuary near Jericho was situated across the Jordan from Baal-peor. From the time of the conquest, Gilgal was an important place of worship (Josh. 4:19–5:12; 1 Sam. 10:8; 11:12–15). Later in Israel’s history, Gilgal became associated with wicked and syncretistic religious practices (9:15; 12:11; Amos 4:4).
As the Lord lives. This orthodox oath (Judg. 8:19; Ruth 3:13; 1 Sam. 14:39) was forbidden here because they were lying (v. 2), or because it was being misused by associating the Lord with Baal worship.