Yahweh’s Spirit came on him, and he judged Israel; and he went out to war, and Yahweh delivered Cushan Rishathaim king of Mesopotamia into his hand. Judges 2
"He judged Israel"
Thus I grant to you a kingdom, just as my Father granted to me, that you may eat and drink at my table in my kingdom, and you will sit on thrones judging the twelve tribes of Israel. Luke 22
Judging. Many self-professing Christians bring up the phrase "judge not" in response to criticism or warning aimed at others, but we know we ought to judge rightly. Othniel judged the Israelites when the served the Baals and the Asheroth. This was right judgement; God was already judging them by handing them over to Cushan Rishathaim king of Mesopotamia.
Jesus told the disciples they will judge the twelve tribes of Israel. Revelation 21 speaks of the new Jerusalem having twelve gates, and the wall having twelve foundations, each with the name of one of the twelve "apostles of the Lamb". Perhaps this is where we get the idea of Saint Peter checking names in front of the pearly gates. From that text, I would assume that the twelve angels are the ones guarding the gates (not St. Peter), much like the angelic sentries guarding Eden in Genesis 3.
How did the disciples judge? At this point, he had already told them the shake the dust off their feet if some place rejects them, so this promise must be for something greater. In Acts 2, Peter judges the Jews: "you, by the hands of lawless men, nailed him to a cross and put him to death". They killed the author of life, but God grants repentence even for this sin.
Is it not our job to judge those inside the church? (1 Corinthians 5:12)
But Peter said, “Ananias, why has Satan filled your heart to lie to the Holy Spirit and to keep back part of the price of the land? While you kept it, didn’t it remain your own? After it was sold, wasn’t it in your power? How is it that you have conceived this thing in your heart? You haven’t lied to men, but to God.” Ananias, hearing these words, fell down and died. Acts 3
Peter judged Ananias, one from within the church who had lied to the Holy Spirit for his own name's sake, rather than honoring God.
Keep a good name. If a brother stumbles, help him out! (He probably won't be struck down dead by God, but who knows.)