'Solemn' in the Bible

When the army came to the forest, look! [There was] honey flowing, but no one put his hand to his mouth, for the army was afraid of the solemn oath.

Then a man from the army informed [him] and said, "Your father made the army swear a solemn [oath], saying, 'Cursed be the man who eats food today,'" so the army [is] exhausted.