Question

Which parts of this passage contain a biblical allusion?

So lived the clansmen in cheer and revel a winsome life, till one began to fashion evils, that field of hell. Grendel this monster grim was called, march-riever mighty, in moorland living, in fen and fastness; fief of the giants the hapless wight a while had kept since the Creator his exile doomed. On kin of Cain was the killing avenged by sovran God for slaughtered Abel. Ill fared his feud, and far was he driven, for the slaughter’s sake, from sight of men. Of Cain awoke all that woful breed, Etins and elves and evil-spirits,

Answer 1

"On kin of Cain was the killing avenged by sovran God for slaughtered Abel."

Cain and Able are biblical figures. Brothers that were presenting sacrifices to their god, which is later the God of Abraham, the Jews and Christians as well. God was not satisfied with the offerings of Cain, since Cain had served him not with blood, but Abel did, which very much pleased god. Out of jealousy, Cain killed Abel.

Answer 2

"On kin of Cain was the killing avenged by sovran God for slaughtered Abel. Ill fared his feud, and far was he driven, for the slaughter’s sake, from sight of men. Of Cain awoke all that woful breed, Etins and elves and evil-spirits,"

Cain and Abel are Biblical brothers. Cain killed Abel because he was jealous of him.