Sforno on Exodus 17:8/ספורנו על שמות י״ז:ח׳

1ויבא עמלק, at the sound of the people’s being frustrated with thirst. This is what Moses meant when he recalled the incident 40 years later in Deuteronomy 25,18 describing the Israelites’ state of mind at the time as ואתה עיף ויגע, “you were tired and worn out.” We find the expression עיף linked to water also in Job 22,7 לא מים עייף תשקה, “You do not give the thirsty water to drink.” (Eliphaz accusing Job) We also find the word applied to earth itself in Isaiah 32,2 בארץ עיפה, “in a languishing land.”