What does the inserted discussion of repentance and purity in 2:222 illustrate?

Iʿtirāḍ and the Relative Measure of Ījāz and Iṭnāb — Concluding Volume 1

• Every parenthesis is a single word
• The surrounding discourse loses all connection
• Several clauses can form one connected parenthetical topic
• It has no rhetorical purpose