'Solemn' in the Bible

Jephthah made this solemn vow to the LORD: "If you truly give the Ammonites into my control,

The Israelis asked themselves, "Who didn't come up in our assembly in the LORD's presence from among all of the tribes of Israel?" They had taken a solemn oath concerning those who didn't come up to meet with the LORD at Mizpah that "They will certainly be executed."