Cross and Brown note that one written source for two of the three versions of the sermon has been recorded, the citation of Alcuin's reference to Gildas (271). They go on to argue that impetus exists for the Sermo Lupi in a sermon that Wulfstan edited, by Abbo of Saint Germain-des-Prés. I quote fully the text of Abbo's sermon in Latin as well as the translation of it given by Cross and Brown, as an analogue to the Sermo Lupi ad Anglos:
The Sermon to the Knights
Brothers, every day you see how this realm is going to ruin. Our peasants
and servants and maidservants and all of those who used to keep
our farms and plough our lands, [in the other texts: and paid
us their tribute] whence we should have had both our food and
our clothing and with which we used to buy our horses and
armour, are now dead or captives. What need we have without
these people! We ourselves know neither how to plough nor sow
the lands, nor prune nor cultivate the vines. What shall we do
now? Surely God is angry with us, and this is why all these
evils from pagans and from the barrenness of the soil come upon
us. Surely, as blessed Augustine says, The earth accuses us to
the Lord, and every day cries out that it cannot bear such
wicked dwellers upon it. And for this reason the land does not
yield us good harvests, nor fruits of the trees, nor grass in
the pastures, as it did in the time of good men. Truly, as the
Lord says, There is no good tree that makes bad fruit, nor a
bad tree making good fruit [Lk 6.43]. The good tree is the good
person who makes good fruit, that is, good works; the bad tree
is the bad person making bad fruit, that is, bad works. So, if
ever you have been bad trees before now, from now on be good
trees, that is, good men, and make the fruit of good works, and
in that instant God will have pity and mercy on you.
But how can you please God and get a victory, you who have
your hands forever full of perjuries and plunderings? Whenever
you travel on some journey, you are devouring the poor and
plundering the estates of Gods churches; and this is why your
hands are shackled by the chains of sins, and you are unable to
gain a victory. The Lord God huimself orders every one of us,
saying If you wish to be perfect, go, sell everything you have
and give [it] to the poor [Mt 19.21]. Our Lord commands you to
give your goods to the poor, and contrariwise you take theirs!
Holy Scripture indeed says concerning you plunderers, Neither
shall the greedy possess the kingdom of God [I Cor 6. 10]. But
therefore, if you want to get peace and victory, do what
Zachaeus the rich Jew did. Do you want to know what he did? He
came to our Lord and questioned him: Lord, what shall I do in
order to have eternal life? The Lord answered him: If you wish
to have eternal life, return fourfold whatever you have taken.
And Zachaeus did so, fearing the Lord and fearing Hell, he
returned four shillings to the person he had taken one shilling
of silver from, and for one measure of wine he returned four
measures. He did the same with other things which he took, and
you, whoever can, do the same. And let him who cannot, promise
before God and his angels and before the priests that he will
no longer be a plunderer or a ravager among the estates of the
holy [Wulfstan adds: or in the goods of the poor], and so you
will have God for your helper in all your troubles.
And you must withhold yourselves not only from plundering,
but also from lust and fornication, and from drunkenness, which
is the mother of lust. Surely it is because of these and of
many other sins that your men [other manuscripts (you) vassals]
cannot gain a victory. And if you refuse to accept the example
of your own good forefathers who defended this realm before
you, at least accept that of the Romans, who were heathens
before the Lord Christ was born of the Virgin Mary. These
Romans, indeed, because they lived righteously, chastely, and
soberly, conquered and defeated all nations. You can also take
an example from the Jews who were before the Lords Coming. As
many times as those Jews sinned and denied [Wulfstans gloss :or
offended] the Lord God, foreign nations always came upon them,
and slew and captured them, and burned their strongholds. And
then the Jews who had been led captive into foreign realms
confessed their wrongdoing and then did penance in a foreign
land because they would not do it in their own land. And
because of that penance, our merciful Lord brought them back to
Jerusalem and gave them peace and abundance of good things, and
gave them total victory against the heathens, so long as those
Jews lived righteously. You, likewise, turn to Our Lord, and
live righteously, and soberly, and chastely without concubines,
for as blessed Augustine says: The man who has a concubine is
an adulterer whether he intends it or not, and the concubine is
an adultress whether she intends it or not.
Brothers, listen to what Our Lord is crying to us every day:
Return to Me, and I shall return to you [Mal 3.7], and
wherefore, if you truly turn to God and fear His saints and vow
to God that you will no longer live by plunder but rather by
your justice, in that hour Our Lord at once will return to you,
and if you will lie in lust always As the horse and the mule in
whom there is no understanding [Ps 31. 9], it is much to be
feared that so great an evil will come upon us as the one we
know has come upon the kings and counts and bishops of the
Bretons. King Conam indeed has fled [altered in C to the king
indeed has fled the crown] and abandoned his realm; just so the
other chief men, bishops and counts have fled and have become
strangers in a foreign land. A like evil happened to King
Zedekiah of the Jews. Indeed, after the heathens had devastated
the whole realm of the Jews, at last they came to Jerusalem
where King Zedekiah was and all of his chief men, and, after
seizing the city, the heathens killed the two sons of King
Zedekiah and killed all the chief men of the realm with the
sword in the kings presence, and they blinded King Zedekiah
himself and led him captive with them into Babylon.
France, defend yourself! Do not multiply and increase your
enemies, but as scripture commands, fight for your fatherland;
do not fear to die in Gods battle. Surely, if you are killed in
it, you will be holy martyrs. And learn truly that no man will
die until the term foreknown by God.
Among all swords no man can be slain, if it is not his own
end. For it is written: Thou hast set up limits which cannot be
crossed [Job 14. 5]. And so, go safe into the Lord Gods battle;
and when you enter into Gods battle, all cry out with a great
voice, Christ conquers, Christ rules, Christ reigns. And at
that moment the Devil, the leader of the heathens, will flee
upon hearing such a terrifying shout from the Christians, and
then those heathens will flee after their leader the Devil. And
so you, who have God as your king and leader, will gain the
victory, by the gift of Our Lord Jesus Christ, to whom, with
God the father and the Holy Spirit, is rule and reign into ages
of ages. Amen. (Cross and Brown 281-87)