Ta'anis 7a, according to Rashi there: Go to teach to a proper Talmid. If he is not proper, "Hoy Kol Tzamei Lechu la'Mayim" (55:1; he goes to the Rebbi to learn ¹ ).

Rashi: It is normal to give water to one who is thirsty. You who live in Eretz Teima ² did not do so. Rather, you gave to them salty food and inflated pouches full of air. [The Yisrael] ate and requested to drink. He put the pouch to his mouth; the air entered his innards, and he died.

Rashi, from Tanchuma Yisro 5: When your ancestor was thirsty, did I not reveal a well of water to him (Bereishis 21:19)?!

Radak: Hesayu is like Asayu. It is a metaphor to say that water should go to greet the thirsty. Bnei Kedar will be exiled, and wander in the Midbar. They will not find water to drink. The residents of Teima, when they see them exiled and wandering, must bring their food to them.

Malbim: You residents of Eretz Teima, the refugees of Kedar fleeing the enemy will pass via your land. Bring water to them! It is easy for you to do so, for water was found in Teima; there was a valley there, and water gathered there - "Hibitu Orchos Tema" (Iyov 6:19).

Malbim: Bnei Eretz Kedar always hosted guests, and gave to every wanderer bread and food. At least, you should give to them water, which is cheap!