Acts 11:8

"'On no account, Lord,' I replied, 'for nothing unholy or impure has ever gone into my mouth.'

Romans 14:14

As one who lives in union with the Lord Jesus, I know and am certain that in its own nature no food is 'impure'; but if people regard any food as impure, to them it is.

Mark 7:2

They had noticed that some of His disciples were eating their food with 'unclean' (that is to say, unwashed)

1 Corinthians 7:14

For, in such cases, the unbelieving husband has become--and is--holy through union with a Christian woman, and the unbelieving wife is holy through union with a Christian brother. Otherwise your children would be unholy, but in reality they have a place among God's people.

Treasury of Scripture Knowledge

Summary

But I said, Not so, Lord: for nothing common or unclean hath at any time entered into my mouth.

Bible References

Common

Mark 7:2
They had noticed that some of His disciples were eating their food with 'unclean' (that is to say, unwashed)
Romans 14:14
As one who lives in union with the Lord Jesus, I know and am certain that in its own nature no food is 'impure'; but if people regard any food as impure, to them it is.