Albert Barnes Commentary John 2:3

"And when the wine failed, the mother of Jesus saith unto him, They have no wine." — John 2:3 (ASV)

When they wanted wine. A marriage feast among the Jews was commonly observed for seven or eight days. It is not probable that there would be a lack of wine at the marriage itself, and it is possible, therefore, that Jesus came there some time during the marriage feast.

They have no wine. It is not known why Mary told this to Jesus. It would seem that she had a belief that he was able to supply it, though he had not yet worked a miracle.