Under Byzantine rule and continuing under Islam, pilgrims collected sanctified oil or water poured over relics and sacred objects at holy sites and brought it back in small containers such as those in this case. These liquids were considered to be eulogiai, material blessings. One side of this flask features a standing caliph, an image found on Umayyad coins, suggesting it was used by Muslim visitors to Islamic, or even certain Christian, holy sites, which Muslims are known to have visited during the early Islamic period.
New York. The Metropolitan Museum of Art. "Byzantium and Islam: Age of Transition (7th–9th Century)," March 12, 2012–July 8, 2012.