Adam Clarke on Hebrews 11:38

Of whom the world was not worthy - Yet they were obliged to wander by day in deserts and mountains, driven from the society of men, and often obliged to hide by night in dens and caves of the earth, to conceal themselves from the brutal rage of men. Perhaps he refers here principally to the case of Elijah, and the hundred prophets hidden in caves by Obadiah, and fed with bread and water. See 1Kgs 18:4. David was often obliged thus to hide himself from Saul; 1Sam 24:3, etc.