1 Corinthians 5:1

we have it from all quarters, that incest is practis'd among you, and such as is not among the Gentiles, that of a man's having his father's wife.

James 1:6-8

but let him be fully persuaded of the lawfulness of what he asks: for he that is diffident about that, is like the waves that fluctuate with the wind.

2 Peter 2:14

their eyes are inflam'd with adultery, and unextinguishable vice: they insnare the souls of the inconstant. their minds are practis'd in the arts of avarice: an execrable race, who have deserted the right way,

2 Peter 3:16

as it were in all his epistles, where he takes notice of these things: in which there are some passages that are difficult to understand, which the illiterate, and unstable wrest, as they do the rest of the scriptures, to their own ruin.

Treasury of Scripture Knowledge

Summary

Unstable as water, thou shalt not excel; because thou wentest up to thy father's bed; then defiledst thou it: he went up to my couch.

Bible References

Unstable

James 1:6
but let him be fully persuaded of the lawfulness of what he asks: for he that is diffident about that, is like the waves that fluctuate with the wind.
2 Peter 2:14
their eyes are inflam'd with adultery, and unextinguishable vice: they insnare the souls of the inconstant. their minds are practis'd in the arts of avarice: an execrable race, who have deserted the right way,
2 Peter 3:16
as it were in all his epistles, where he takes notice of these things: in which there are some passages that are difficult to understand, which the illiterate, and unstable wrest, as they do the rest of the scriptures, to their own ruin.

Because

1 Corinthians 5:1
we have it from all quarters, that incest is practis'd among you, and such as is not among the Gentiles, that of a man's having his father's wife.