Andrei Rublev’s icon painting known as the Old Testament Trinity, ca. 1411, housed at the Tretyakov Gallery. The icon’s subject matter alludes to the hospitality that the couple Abraham and Sarah showed to the three angels who visited them. Image source (public domain): https://en.wikipedia.org/wiki/Russian_icons#/media/File:Angelsatmamre-trinity-rublev-1410.jpg.
