This motif is a bit of a mystery to me! — I wondered if it is some historical reference to the uprisings of 1525? The Deublinger album inscription seems to suggest it’s a Three Musketeers “All for one, and one for all” sentiment.

The first print-book to notice the motif is Rollos’ Euterpe Suboles [Berlin 1924] but it is found earlier in the albums — though unfortunately I do not have a copy of the miniature, it appears in the album of Rhaban Giese in an entry dated 1618 — and see the auction catalogue excerpt below (1612).

Not sure which Psalm the captioning verse is referring to — any offers?

Wir seindt zwar drey vnd doch nur Ein We are three indeed and yet but one

Dann vnder Vns alls ist Gemein since amongst us all is common

Hertz Sinn vnd muth, all haab vnd guth heart mind & courage, all goods & wealth

Einer furn andern auffsetze[n] thut ………………..