[If] two saw him from this window, and two saw him from that window, and one in the middle warned him —- if some of them saw each other, then they are one set of witnesses; if not, they are two sets of witnesses. Therefore, if one of them is found to be zomemim, both he and they are executed, and the second [set] is exempt. R' Yose says: They are not executed unless his two witnesses warn him, as it is said (Deut. 17:6): By the testimony of two witnesses. Another explanation: By the testimony of two witnesses —- that a sanhedrin should not hear [testimony] from the mouth of an interpreter.