وَوَضَعْنَا عَنْكَ وِزْرَكَ الَّذِي أَنْقَضَ ظَهْرَكَ
And We removed from you the burden that had weighed upon your back.
Verse 94:2 mentions wizr, and 94:3 uses the relative clause alladhī anqaḍa ẓahrak to describe its weight. The second verse completes the reference in the previous one rather than introducing an unrelated new subject.
The image of a burden weighing on the back intensifies the description. The rhetorical connection includes syntax through a relative clause, not just the initial conjunction.