Here are my notes on the issue:
There is an essay called Traces of the Ebionean Gospel, by L Wallace, that you can read here:
http://www.jstor.org/stable/3262461?log ... b_contents
The author proposes that a saying by Rabbi Gamaliel in the Talmud is used against the Ebionites (and not itself an Ebionite saying). Wallace points to the story of Imma Shalom (that you can read here:
http://www.jewishvirtuallibrary.org/imma-shalom), where a Christian judge says that the Law is superseded by the Gospel, and then Gamaliel says that in the Gospel, Jesus says he did not come to overturn the law, referring to a quote in Matthew. Wallace sees the judge's reaction as Ebionite, but I am not sure of this. It seems to me that there is a sense in which in Christianity the Law is superseded, and in another sense in which it is not. Tertullian writes about the disposal of the law as designed by the disposition/desire of the Creator, and that the spiritual worship aspect of the Law remains in force.
Wallace notes though that this same section of the Talmud, B. Shabbat 116, sees a difference between "Ebionites" and "Nazoreans". The story about Imma Shalom could be dealing with a special aspect of the Ebionites that distinguishes them from the Nazoreans. Wallace writes about the Ebionites: "In their opinion the system of the sacrifices as codified by the Jewish law had been supplanted by the baptism. For this reason they did not hesitate to be critical of the transmission of the OT, an attitude to which [the story of Imma Shalom] clearly testifies." However, I think that this doesn't well describe the views of the judge in the story. There, the judge saw the law as legitimate but superseded, whereas the Ebionite view was that the sacrifices were not legitimate in the first place. The Ebionites did not accept David or the prophets after him either.
Wallace also sees the story as referring to the judge as Ebionite because of the theme of division of a house. Wallace points to the book "Syrian Theophany", which says: that Jesus
dominates the whole world through these [words]: 'I have come to split, to bring down the sword and the split upon mankind'...[he] splits all the houses... so that some think the way he does, while the others oppose him...he taught the cause of the split of the souls, which would take place in the houses, as we have found it written somewhere in the Gospel, that is spread among Jews in the Hebrew tongue.
In the Ebionite Pseudo-Clementine writings, there is a discussion on dividing souls between male and female souls (eg. Adam vs. Eve), so I could see how the brother-sister dispute in the Talmudic story of Imma could be related to the Ebionite theory of dividing souls.
Wallace mentions an idea that the saying in Matthew 5,
"Neither do people light a lamp and put it under a bowl. Instead they put it on its stand, and it gives light to everyone in the house", or a similar Jewish saying not to put a lamp under a bushel, has been changed at the end of the story in the Talmud to Gamalie's "The ass knocked over the lamp". To clarify, this is not an Ebionite saying, but one that the Talmud story used against Christianity.
So first, Santos is incorrect if he wrote in his book (that you read) that Wallace thinks this is an Ebionite saying. The whole point of Wallace's essay was to describe the proverb as anti-Ebionite.
Second, I doubt that the judge in the Talmud story was Ebionite and not just Christian.
1. Wallace thinks the judge was Ebionite because elsewhere this Talmud section differentiates Ebionites from Nazoreans.
But the Talmud story doesn't say if the judge was Ebionite or Nazorean.
2. Wallace also thinks that the judge was Ebionite because the judge talks about the gospel superseding the old law. However, the supersession of the Law, at least in some sense, was a mainstream Christian belief as laid out by Tertullian and the apostle Paul (Hebrews 8:13). In contrast, the vegetarian Ebionites said that they didn't even believe that parts of the law like sacrifice were valid in the first place, whereas other parts of the Mosaic ritual covenant they still ritually observed. The Ebionite ideology therefore was definitely not supersessionist.
There is a very common confusion in academic circles between Biblical Christianity's "Supersessionism" (belief that the Torah has in some ways been superseded) and Marcion's and others' belief that the Torah or parts of it were never valid int he first place.
3. Wallace sees the Talmud story about dividing inheritance between a sister and a brother as Ebionite because it talks about dividing a house based on religious fractions. However, the gospel itself talks about how religion divides houses, so
I don't find this Talmud story about the judge as particularly Ebionite for this reason either.