This scene is not described in the Bible, but formed part of medieval devotional literature. Christ looks out at the viewer, inviting the meditation on his suffering which such literature usually invited.
The picture appears to have formed the central part of a small altarpiece with shutters which survive in Antwerp. These include the figures of the Virgin and Saint John the Evangelist. The distant figures on the left wear headdresses reminiscent of early 15th-century fashion and appear to have been copied from a Van Eyck 'Crucifixion' (now New York, Metropolitan Museum of Art) of that period. The background on the right is badly damaged.
This is an early work by David, perhaps before he became established in Bruges.
From The National Gallery Podcast: Episode Forty Four, June 2010