Understanding and application

What does لَمْ do in مَنْ لَمْ يَشْكُرِ النَّاسَ?

Humility, Gratitude, Goodwill, and Conditional Sentences (Hadith 188–198)

• Turning the noun into a plural
• Negating the present-tense verb and making it jussive
• Making the verb past-tense plural
• Issuing a command rather than a negation