To a follower of Muhammad this might seem like a non-contradiction at first glance. When Iblees disobeyed Allah, he was cursed to eternity in Jahannam (a kind of combination between the Christian concepts of hell and purgatory). If this is true, then there is no contradiction because verse 30:26 mentions only things in heaven and on earth. Jahannam is neither.
But not so fast. Verses 7:14-15 tell us the story of what really happened. When Iblees was cursed to Jahannam, he begged Allah for reprieve until judgement day. Allah agreed. Although Allah banished him from heaven in verse 7:18, he was not sent to hell. Considering that there are only three options here — heaven, hell, and the earth — Iblees must be on earth. In other words, Iblees is on earth and has disobeyed Allah. The contradiction is complete.
One final piece of trivia. Verse 2:34 is exceptionally humorous. It claims that Iblees’ arrogance made him one “of the disbelievers.” In other words, despite Iblees having direct knowledge that Allah exists and that Islam is the true religion, he did not believe it to be true. That would be like me not believing that fire burns, even though I have perfect evidence that it does burn. It appears that this verse was trying to equate non-Muslims with devils, but did so in a way that makes Allah seem idiotic.