This passage occurs as the recommend Reformation Sunday passage.
Summary: I have never understood why this is a Reformation text. It talks a lot about law and seems to remove the simul from the saint and sinner dialectic so essential for Lutheran thinking. For me the most reformation insight here is that truth is Jesus Christ. John's Gospel was not simply calling us to right thinking or apprehension of some set of facts, but in the Gospel of John, Jesus invites his followers to know him. In the same way, Martin Luther didn't invite people to accept a set of tenets but invited them to know Christ and his benefits.
Ιουδαιους ("Judeans" or "Jews", 8:31). This word is problematic for modern translators. If we translate it as Jews, we think of, perhaps rich bankers on wall street or modern Israelis. Jesus is referring to the people in the country side who believed in YHWH and practice Mosaic law. In otherwords, to translate it as Jews misses out on the geographic and political realities of its day. However, to translate it Judeans misses out on all of the religious connotations of the Mosaic law. Good to remember that Jesus is not necessarily simply preaching to the Jewish people living today, but anyone who commits a sin. The enemy in this text is not the Jewish law, but entitlements and moral laxity.
μεινητε ("abide", aorist form μενω, 8:31 and 35). A key motif of the entire Gospel is abiding in Jesus. The NET translation offers, "If you continue to follow my teaching." This may push this too far, but abiding in Jesus' words certain carries with it an expectation of following Jesus teachings.
αληθεια ("truth", 8:32) It is worth remembering that in the Gospel of John, truth is not a proposition or a collection of facts, but it is the person of Jesus Christ. If you follow me, you will know me, and I will set you free...is another way to hear this verse.
Some tenses worth noting
8:31: ελεγεν is imperfect, suggesting that Jesus had to repeat this more than once...
8:31: μεινητε is aorist. I would suggest this is an "inceptive" aorist meaning the action begins. The previous verse talks about new conversions. This verse says, look, now that you are believing, begin to stay in my word and then you will be my disciples. The only problem with making this an inceptive is that it splits apart believing and being Jesus disciple, something that seems incoherent for John's Gospel. However, perhaps Jesus points to a reality here that discipleship requires faith; but not all faith means discipleship (sadly).
8:32: γνωεσθε (know) and ελευθερωσει (being set free) are both in the future tense; whereas being a disciple is in the present, suggesting that discipleship may preceed knowing the truth rather than be based on it.
8:33 δεδουλευκαμεν is perfect. Perfect means past action with present reality. Probably best to translate this: We have never been enslaved. Which is not really true because they were slaves in Egypt. But if we really take the perfect to mean what it should, perhaps they are being more honest (even if wrong) in that they are currently not under the yoke of slavery. (Which again is false).