Here you go! Montgomery, James E. “Ibn Faḍlān and the Rūssiyah.” Journal of Arabic and Islamic Studies 3 (2000): 1–25. Just click the pdf link on the right of the page. Montgomery offers a good introduction to the text and then a scholarly translation beginning at p.5, all with excellent footnotes.

Want more? The best edition of Ibn Fadlan for scholarly use can be found in Two Arabic Travel Books, which includes a full translation by Montgomery. A cheaper but still excellent alternative is Ibn Fadlan and the Land of Darkness. It starts with a full translation of Ibn Fadlan, followed by a selection of other early Arabic writers who discuss the Rus, Slavs, Khazars, etc. Plus, since it's a volume that's often assigned for Vikings classes, there's generally used copies available for cheap.

Interested in some rigorous discussion of what the heck we should make of this strange source? In addition to Montgomery's introductions and notes, check out the work of Thorir Jonsson Hraundal, who's shared two publications on academia.edu. (You might need to register to download, but it's free.) His PhD thesis is a solid analysis with tons of brilliant insights on Ibn Fadlan and other Arabic authors who discuss the Rus. The other article captures the key takeaways in shorter form. I find that Montgomery gives me the grit I need to understand the text, but Jonsson Hraundal helps me answer a lot of questions that Ibn Fadlan raises.