Lan: active | passive
FormActivePassive
Second-person masc. singularلَنْ تَفْعَلَلَنْ تُفْعَلَ
Second-person masc. dualلَنْ تَفْعَلَالَنْ تُفْعَلَا
Second-person masc. pluralلَنْ تَفْعَلُوالَنْ تُفْعَلُوا
لَنْ تَفْعَلَ means ‘you (one male) will not do’. In the dual and plural, the alif or wāw remains while inflectional nūn drops.
لَنْ تَفْعَلَا — you two will not do.
لَنْ تَفْعَلُوا — you (masc. plural) will not do.
All these are future-negative statements; they are not imperatives or prohibitions.