Juan de Flandes
The Baptism of Christ

1508/1519
oil on panel, 48 7/8 x 31 1/16 inches
National Gallery of Art, Washington

The angel's garb suggests the liturgical garment called the alb, worn by all ministers in a liturgy to symbolize their own baptism.  Hanging at the angel's left flank is what appears to be another liturgical garment, the stole.

More of the Baptism of Christ

Source: National Gallery