This quote comes under Pācittiya 74 on giving a bhikkhu a blow out of anger.
Buddhist Monastic Code wrote:
Non-offences. According to the Vibhaṅga, there is no offence for a bhikkhu who, trapped in a difficult situation, gives a blow desiring freedom. The Commentarys discussion of this point shows that it includes what we at present would call self defence; and the K/Commentarys analysis of the factors of the offence here shows that even if anger or displeasure arises in ones mind in cases like this, there is no penalty.
Summary: Giving a blow to another bhikkhu when motivated by anger is a Pācittiya offence.
Whatever monk, angry, displeased, should give a monk a blow, there is an offence of expiation.”
Whatever means: … monk is to be understood in this case.
A monk means: another monk.
Angry, displeased means: dissatisfied, the mind worsened, stubborn.
Should give a blow means: if he gives a blow with the body or with something attached to the body or with something that may be cast, and even with a lotus-leaf, there is an offence of expiation.
If he thinks that one is ordained when he is ordained, (and) angry, displeased, gives a blow, there is an offence of expiation. If he is in doubt as to whether one is ordained … If he thinks that one is not ordained when he is ordained, (and) angry, displeased … offence of expiation. If angry, displeased, he gives a blow to one who is not ordained, there is an offence of wrong-doing.
Monks, as low-down thieves
might carve one limb from limb
with a double-handled saw,
yet even then whoever sets his mind at enmity,
he, for this reason,
is not a doer of my teaching.
Herein, monks, you should train yourselves thus:
‘Neither will our minds become perverted
nor will we utter an evil speech,
but kindly and compassionate will we dwell,
with a mind of friendliness,
void of hatred;
and we will dwell having suffused that person
with a mind of friendliness;
and, beginning with him,
we will dwell having suffused the whole world
with a mind of friendliness that is far-reaching,
This is how you must train yourselves, monks.
 If you, monks, were to attend repeatedly
to this exhortation on the Parable of the Saw,
would you, monks,
see any way of speech,
subtle or gross,
that you could not endure?"
“Wherefore, monks, consider repeatedly this exhortation on the Parable of the Saw;
for a long time it will be for your welfare and happiness.”
Thus spoke the Lord.
Delighted, these monks rejoiced in what the Lord had said.
Discourse on the Parable of the Saw
(The link below has the unabridged PTS translation with all repetitions rolled out for you. It is formatted as poetic verse.)