What is the grammatical effect of lam on yalid?

Supplementary Practice 23: Comparative Rhetorical Study of Sūrat al-Masad and al-Ikhlāṣ

• Makes the imperfect subjunctive and affirmative future
• Converts the verb into an active participle
• Makes the subject genitive
• Makes the imperfect jussive and gives past-oriented negation