Focus on The Fingernail Test and explain the Painting.
The painting is also known as Boy with a glass and a lute and shows a young lute-player wearing a beret and a draped cloak over his chest, tilting his glass to show it is empty while facing the viewer in order to say "time is up". It was attributed to Hals for centuries until Claus Grimm called it a product of his circle. According to Hofrichter, the positioning of a figure sitting behind a table is a typical Leyster theme, and the upward glance is reminiscent of her Violin player, while the application of paint is similar to her Two children with a cat.
Claus Grimm