sn The Greek word translated set … apart (ἁγιάζω, hagiazō) is used here in its normal sense of being dedicated, consecrated, or set apart. The sphere in which the disciples are to be set apart is in the truth. In 3:21 the idea of “practicing” (Grk “doing”) the truth was introduced; in 8:32 Jesus told some of his hearers that if they continued in his word they would truly be his disciples, and would know the truth, and the truth would make them free. These disciples who are with Jesus now for the Farewell Discourse have continued in his word (except for Judas Iscariot, who has departed), and they do know the truth about who Jesus is and why he has come into the world (17:8). Thus Jesus can ask the Father to set them apart in this truth as he himself is set apart, so that they might carry on his mission in the world after his departure (note the following verse).