لِيَحْجُزْكَ عَنِ النَّاسِ مَا تَعْلَمُ مِنْ نَفْسِكَ
“Let what you know of yourself restrain you from preoccupation with other people's faults.”
لِيَحْجُزْكَ expresses restraint or prevention. Awareness of one's own weaknesses should reduce arrogance and promote reform. This does not cancel the duty to offer necessary advice or help the oppressed; the warning concerns habitual fault-finding.
Example
Someone repeatedly exposes others' small mistakes while neglecting their own harsh speech. A better approach begins with examining one's speech and offering others dignified, constructive counsel. In مَا تَعْلَمُ مِنْ نَفْسِكَ, مَا refers to what one knows about oneself.