Frederick Rihel (1621 - 1681) came from Strasbourg and is first mentioned in Amsterdam in 1642, remaining there as a successful merchant until his death in 1681. As an official of the civic guard he took part in the procession which welcomed the Prince of Orange into Amsterdam in 1660.
This seems to be the occasion portrayed here judging by Frederick Rihel's ornate dress and the glimpses of the procession winding along behind him. Rihel wears a buff jerkin with sleeves and cuffs decorated with gold thread; he has a large white sash, sword and pistol and rides a horse which is performing a levade.
Attribution of this painting to Rembrandt has on occasion been questioned on the grounds that the horse is more stiffly painted than the figure. This may be explained by the fact that Rembrandt rarely painted horses. The inventory of Rihel's possessions made after his death mentions a portrait of him on horseback by Rembrandt, suggesting that the attribution is correct.