Luke 8:30

And Jesus asked him, saying, What is thy name? And he said, Legion: because many devils were entered into him.

Cross-reference

Matthew 8:29 records the demons' question to Jesus — the parallel account of this same encounter, giving their words in more detail.

Mark 5:9 Parallel

Mark 5:9 records the identical exchange where the demon says 'Legion, for we are many' — a direct parallel of this verse.

Matthew 8:31 has the demons begging to be sent into the pigs — the direct continuation of this naming account in the parallel gospel.