The inscription reads:baraka li-sahibihi , 'amal muhammad ibn al-ahzan(?) (Blessing to the owner. The work of Muhammad ibn al-Ahzan (?)).
A small group of ewers of comparable form are known, almost all of which are of colourless glass. Two are in the al-Sabah Collection, with inscriptions that have been interpreted as indicating that they were made in Baghdad (Stefano Carboni, Glass from Islamic Lands, London, 2001, cat.48a and b, pp.200-201). These were first discussed at length by David S. Rice ("Early Signed Islamic Glass", Journal of the Royal Asiatic Society of Great Britain and Ireland, April, 1958, pp.8-16).
The rich turquoise colour and the depth and clarity of the inscription on this bottle make it stand out from among the rest of the group.