To identify tafrīʿ, determine the first subject and judgment, locate the new judgment, and ask whether the latter is rhetorically dependent on the former. Removing the first clause should normally weaken the significance of the second.
Compare: “His learning is a light, and his speech illuminates hearts,” where the second effect is related to the first attribute, with “His learning is a light, and he travels,” where no similar link is established by the statement itself.
This is a test of semantic relation, not a mechanical requirement that two clauses be placed together.