اِقْشَعَرَّ ends with a doubled rāʾ. The source therefore records forms with consonant assimilation and with the doubled consonants pronounced separately.
اِقْشَعِرَّ — اِقْشَعْرِرْ
Translation: let your hair stand on end; two imperative pattern forms.
لَا تَقْشَعِرَّ — لَا تَقْشَعْرِرْ
Translation: do not let your hair stand on end; prohibitive pattern forms.
The first type keeps the consonant assimilation; the second separates the repeated rāʾ. Since the event is normally involuntary, these commands are uncommon in ordinary use, but the morphological alternation is meaningful.
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Command and prohibition of iqshaʿarra
The Four Unaugmented and Augmented Quadriliteral Patterns
اِقْشَعَرَّ ends with a doubled rāʾ. The source therefore records forms with consonant assimilation and with the doubled consonants pronounced separately.
اِقْشَعِرَّ — اِقْشَعْرِرْ
Translation: let your hair stand on end; two imperative pattern forms.
لَا تَقْشَعِرَّ — لَا تَقْشَعْرِرْ
Translation: do not let your hair stand on end; prohibitive pattern forms.
The first type keeps the consonant assimilation; the second separates the repeated rāʾ. Since the event is normally involuntary, these commands are uncommon in ordinary use, but the morphological alternation is meaningful.