It happens to be that I personally have never observed the custom you are describing. Nevertheless, I was able to find a source.
The Beit Yosef (OC 651) cites that this practice was defended by Tosfot (this view is found in our versions of Tosfot to Sukkah 37b, d.h. behodu; link):
ועכשיו שנהגו שש"ץ אומר יאמר נא והצבור עונין הודו וכן ביאמרו נא בית אהרן ...
Found it. It was written by Rabbi Meir ben Shimon of Narbonne in a letter he wrote against the Kabbalah (published by Adolf Neubauer in JQR 4:3, pg. 358):
"...וכבר הגיע אותו ספר לידינו ומצאנו בו שתלו אותו בר' נחוניא בן הקנה חס ושלום לא היה ולא נברא ולא נכשל בו אותו צדיק..."
Translation: "...And this book has just come into our ...
It is from the Rambam's introduction to the Eight Chapters
Know, however, that the ideas presented in these chapters and in the
following commentary are not of my own invention; neither did I think
out the explanations contained therein, but I have gleaned them from
the words of the wise occurring in the Midrashim, in the Talmud, and
in other of their works,...
In addition to the excellent answer of @Dov I would add a link to minhag-resources on the website of the Dutch Jewish Community.
There is a mix of modern and pre-war; Most of the info is curated with the express purpose of maintaining the minhagim of prewar and just post-war communities. Much of the ...
The "he" refers to the speaker, in this case Moses. Abarbanel quotes the book of Yosiphon as saying that some of the troops used by Rome in the destruction of the second Temple came from Britain/England.
The Ohr HaChaim has a whole piece on it.
It writes in Parshas Vayechi 47:29
וַיִּקְרְב֣וּ יְמֵֽי־יִשְׂרָאֵל֮ לָמוּת֒ וַיִּקְרָ֣א ׀ לִבְנ֣וֹ לְיוֹסֵ֗ף וַיֹּ֤אמֶר לוֹ֙ אִם־נָ֨א מָצָ֤אתִי חֵן֙ בְּעֵינֶ֔יךָ שִֽׂים־נָ֥א יָדְךָ֖ תַּ֣חַת יְרֵכִ֑י וְעָשִׂ֤יתָ עִמָּדִי֙ חֶ֣סֶד וֶאֱמֶ֔ת אַל־נָ֥א תִקְבְּרֵ֖נִי בְּמִצְרָֽיִם׃
And when the time approached for Israel to ...
Rabbi Philip Biberfeld in Universal Jewish History, vol 2, argues that there were at least some practical implications for priestly roles in how the Avot lived their lives:
"From Biblical records one can deduce that originally neither priests nor temples existed. Worship was conducted by the head of the family and entrusted to the firstborn son...In ...