The seventh day of Sukkot, also known as The Great Last Day.
The New Testament records that it was on the last day of Sukkot (i.e., “the great day”) – and most likely after the water libation – that Yeshua stood up and cried out, “If anyone thirsts, let him come to me and drink!”
37 On the last and greatest day of the Feast, Yeshua stood up and cried out loudly, “If anyone is thirsty, let him come to Me and drink. 38 Whoever believes in Me, as the Scripture says, ‘out of his innermost being will flow rivers of living water.’” [a] 39 Now He said this about the Ruach, whom those who trusted in Him were going to receive; for the Ruach[b] was not yet given, since Yeshua was not yet glorified. (John 7:37-39