Troost, Cornelis – Portret van een lid van de familie Van der Mersch, 1736 Rijksmuseum: part 3

The picture has something of this: people, woman, portrait, room, furniture, wear, music, man, two, instrument, seat, musician, group, jacket, pants, weapon, indoors.
Perhaps it’s a painting of a man sitting at a desk with a sheet of paper in front of him and a violin on the table.