During Jesus's prayer to the Father, Jesus talked about what He did while on Earth. Jesus "manifested [the Father's] name" to people the Father gave Jesus (17:6). With the manifestation, various people -- especially the original disciples -- learned about who the Father is (especially Jesus's link to the Father). The original disciples aren't just Jesus's disciples; they are also the Father's disciples.
The people that the Father gave to Jesus got to know that "all things which [the Father gave Jesus] are from [the Father]" (17:7). Jesus is likely referring to the miracles and the teachings. In fact, regarding the words, the people that the Father gave to Jesus "received them" and "known surely that [Jesus] came forth from [the Father]" and "believed that [the Father] sent [Jesus]" (17:8). When people like the disciples accept Jesus's words, they were in essence accepting the Father's words because Jesus's words originated from the Father.