An interesting conversation takes place between Yaakov and his opponent as they end their struggle. Yaakov had crossed over Nachal Yabok to retrieve some small pots that he had forgotten. He was met on the other side by a man who began to battle him. Chazal tell us that this man was none other than Eisav’s guardian angel, his spiritual counterpart. As the fight concludes, Yaakov and this angel have a strange conversation. The angel asks Yaakov to let him go because the sun is rising. Yaakov demands a blessing, though, before he allows the angel to leave. The angel gives him the name, “Yisrael.” Yaakov subsequently inquires as to the angel’s name. The angel gives a strange reply (32:30), “Lamah Zeh Tishal LiShmi,” “Why do you ask for my name?”
Rabbi Frand makes an interesting observation regarding this point. The angel, instead of replying, “I don’t need to tell you my name,” or, “I’m not allowed to tell you my name,” asks, “Why do you need to know my name,” implying that Yaakov would derive some benefit from knowing the angel’s identity.
Rashi tells us that angels do not have definite names. Instead, they receive a name based on their current mission. This angel had the name Sama’el, the spiritual angel of Eisav and the nemesis of the Jewish people, the Satan. His goal was and still is to oppose Bnei Yisrael throughout the generations. Accordingly, why was he opposed to telling Yaakov his name?
Rav Samson Raphael Hirsch explains Sama’el’s opposition to telling Yaakov his name. Rav Hirsch equates the Hebrew words Shem (name) and Sham (there), showing that a name can describe an object. A name describes the core of an object, where and of what the object consists.
This answer makes the angel’s response to Yaakov understandable, but it also allows us to re-examine Yaakov’s question. When Yaakov asked for the angel’s name, he was trying to find the essence of the Satan. He was trying to assist his descendants in their fight against evil by asking the way in which the Satan fights. The angel replies that the knowledge of his name isn’t necessary nor is it helpful to Yaakov because he has more than one manifestation. His battle against us would change as the times dictated. He doesn’t have an exact definition, and therefore he has no name. It is our job to constantly look out for the Satan and to guard ourselves against him in all of his forms.