“Hey!” The Hebrew term hoy (#01945,הוֹי), is an interjection that was used in different contexts and has to be translated in a way that fits with the context, and possible translations include “ah, alas, oh, woe, O, ho,” etc.). It was used in hard and difficult times such as deaths and funerals, and often is used in prophecies of judgment to catch the people’s attention. However, sometimes it was just used to get the reader to pay attention, and that seems to be the case here in Isaiah 55:1.

“all you who are thirsty.” This invitation is general and includes all humanity, not just Israel, as we see from the context, especially Isaiah 55:5.