Avraham Avinu had three close friends and confidants: Avner, Eshkol and Mamre, whom he consulted when he was commanded to circumcise himself. Avner advised him not to do it because of his advanced age. Eshkol presented arguments in support of Avner’s advice. He felt that in Avraham’s weakened condition post-circumcision, his enemies would be able to overpower him. Mamre encouraged Avraham to circumcise himself. When the meraglim, spies, came to Eretz Yisrael, they stopped at Nachal Eshkol and picked a cluster of grapes which they brought back to Moshe.
Horav Eli Munk, z.l., suggests an analogy between the episode of the spies returning with a cluster of grapes and the name Eshkol. The spies brought back the grapes to support their position that, just as the fruit of the land was abnormally large, so, too, were its inhabitants unusually powerful. This is why that place had already been called Eshkol at the time of Avraham’s circumcision. It was characterized as a place where one’s fear of future enemies would dishearten him from doing the right and proper thing today. In other words, Nachal Eshkol is a place that characterizes a lack of bitachon, trust in the Almighty. It is interesting that the meraglim seemed to gravitate to that one place in Eretz Yisrael where their lack of faith would appropriately fit in.