وَإِذْ آتَيْنَا مُوسَى الْكِتَابَ وَالْفُرْقَانَ لَعَلَّكُمْ تَهْتَدُونَ
Wa iz aataynaaa Moosal Kitaaba wal Furqaana la'allakum tahtadoon
And remember when we gave Musa the Scripture and the criterion, so that you might be guided.
Commentators have never agreed on whether the criterion is a second thing given alongside the Scripture or another name for it, and both readings are old. Arabic grammar allows either, since the conjunction can join two things or restate one. The choice matters little for the closing purpose, which is guidance, and the same root has already appeared in this passage for the parting of the sea.