skin.

marrow > {The vital part or "core" of the body}

6 Which to extirp, he laid him privily

extirp > extirpate
privily > secretly; _hence:_ away from view

7 Down in a darksome lowly place far in,
8 Where he meant his corrosives to apply,

corrosives > remedies, caustic drugs

9 And with strait diet tame his stubborn malady.

strait > strict
diet > {Way of living or thinking}
stubborn > unyielding, intractable (cf. 108.25:4)

110.26

In ashes and sackcloth he did array
2 His daintie corse, proud humors to abate,
And dieted with fasting euery day,
4 The swelling of his wounds to mitigate,
And made him pray both earely and eke late:
6 And euer as superfluous flesh did rot
_Amendment_ readie still at hand did wayt,
8 To pluck it out with pincers firie whot,
That soone in him was left no one corrupted iot.

1 In ashes and sackcloth he did array
2 His dainty corse, proud humours to abate,

dainty corse > handsome body
proud > proud, arrogant; lascivious; swollen, superfluous
humours > {Habits of mind; mental qualities, inclinations; also: the
four cardinal "humours" of the body whose proportions, in
medieval physiology, were believed to determine one's mental and
physical qualities}
abate > destroy; abate

3 And dieted with fasting every day,
4 The swelling of his wounds to mitigate,
5 And made him pray both early and eke late:

eke > also

6 And ever, as superfluous flesh did rot,
7 Amendment ready still at hand did wait,
8 To pluck it out with pincers fiery hot,
9 That soon in him was left not one corrupted jot.

That > [So that]

110.27

And bitter _Penance_ with an yron whip,
2 Was wont him once to disple euery day:
And sharp _Remorse_ his hart did pricke and nip,
4 That drops of bloud thence like a well did play;
And sad _Repentance_ vsed to embay,
6 +His bodie in salt water smarting sore,+
The filthy blots of sinne to wash away.
8 So in short space they did to health restore
The man that would not liue, but earst lay at deathes dore.

6 His bodie in salt water smarting sore, > His blamefull body in
salt water sore, _1590_

1 And bitter Penance, with an iron whip,
2 Was wont him once to disple every day:

Was wont > Was accustomed; used
disple > discipline (esp. as a religious practice)

3 And sharp Remorse his heart did prick and nip,
4 That drops of blood thence li