He will separate people one from another, just as a shepherd separates the sheet from the goats. This taken from Matthew 25:32.
In the illustration of the sheep and goats, Jesus does not directly mentioned the preaching work. Why, then, can it be said that it emphasizes the importance of preaching? Note that Jesus is teaching by means of an an illustration. Obviously, he is not talking about separating the literal sheep from literal goats. Likewise, he is not saying that each individual judged to be a sheep must literally feed, clothe, nurse, or visit one of his brothers in prison. Rather, he is illustrating the attitude that the figurative sheep display towards his brothers. He describes the sheep as “righteous” because they recognize that Christ has a group of anointed brothers still on earth, and the sheep loyally support the anointed during these critical last days. With him, his sheep they’re sleeping playing the good news of the kingdom. (Matthew 10: 40-42; 25:40, 46; 2 Timothy 3:1-5)