"So I will never be a helper to the criminals," meaning: a supporter. Qatada said: He is saying, "I will never support a wicked person after this."
﴿فَلَنْ أكون ظهيرا﴾ أَي: عوينا ﴿للمجرمين﴾.
قَالَ قَتَادَةُ: يَقُولُ: فَلَنْ أُعِينَ بعْدهَا على فجرة
